CEM Wiring/Repair Information

[Russell_S]

Hi, I've recently had a headlight problem which, at first, appeared to be the common CEM issue (see this thread http://www.volvoforums.org.uk/showthread.php?t=67437) but finally turned out to be a break in the wiring loom. However, while fault finding the problem I found out a bit about the CEM which I thought others could find useful in faulfinding their own headlight related issues. I've taken a few pictures to help with this.

I have attached to this thread the Volvo wiring diagram for the CEM and headlights because the Haynes manual is worse than useless in this respect as it doesn't even show the CEM in their wiring diagrams.
I have also attached the data sheet for the Fujitsu relays that are used for the headlight switching in the CEM. I originally assumed that they would be solid state relays but in fact they are normal miniature PCB mounting mechanical relays so it they do fail then the data sheet could help find a replacement to repair the CEM.

Firstly, for those who don't know where the Central Electronics Module (CEM) is situated, here is a picture:
http://i93.photobucket.com/albums/l74/RussellS_2006/CEMLocation.jpg


Next we have a picture of the CEM circuit board itself highlighting the headlight relays:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMPCBRelays.jpg


and now a picture of the CEM connectors and their pin numbering to go with the attached wiring diagram:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMConnectors.jpg


Hopefully others will find this information useful as the CEM does appear to be a weak component with respect to headlight switching.


Regards

Russell

[coupeboy]

Wow- thanks for the info. Always wondered how the headlights knew to dim when starting the engine - a clever box of tricks until it goes wrong. Think l'll be paying a trip to the scrappy before attemting repair of a CEM!

[Mark Quintet]

Does anybody know anyone who can repair CEMs if they have a relay problem? But thanks for the post.

[spickee]

Got a headlight problem with mine. Don't know what it is though or how to fault find any more than I already have. No voltage on the left side head light, only getting about 1.3v at the fuse box. Right hand headlight fine. Side lights fine. Full beam fine on both sides. Anyone got any more suggestions or do I need to take it to the garage. Cheers

[Dog_Book]

I wonder if this unit can be altered to turn off the DRL's :P

[DeeJay]

Oh bu**er!

O/S dipped head light not on (I use DRL's). Did the normal, changed the bulb, no joy.

Checked the fuses, relays and had a look at the loom (under the radiator) with no fault found.

Had the car in for some other work and they traced the defect to the CEM. Glad I was sitting down when the service guy rang me to give me the "good news" - along with the cost of a replacment new unit + labour for fault finding and replacement + (of course!) Darling's 15%!

Of course the bloody light is working fine now! Agree that Haynes is as much use as a chocolate fire guard, but if I get a repeat of this fault I'll know where to look!

[viavan]

Thanks for the post, headlight dip light doesn't work. trace the problem back to one of the relay in the CEM, VOLVO quote 400 plus for the whole CEM unit. Scrap yard 50 pounds. But you can also buy the Fujitsu relay as a component from sales@inelcohunter.co.uk. not too sure how much each relay cost, because i managed to repair the faulty relay (due to dry joint).

[viavan]

I do agree that the Haynes manual is useless!

[host07]

Did someone know, which of this is the rear wiper relay?

[960kg]

Did someone know, which of this is the rear wiper relay?

......the relay is in the cabin fusebox as pic....don`t know what year or model yours is but i expect it is in the same place....

[host07]

Thank you for your picture, I really want this VADIS :-)

Unfortunatly the wiper relay has to be located in the CEM in my car model, the location you showed was in previous models though.

My car is a year 2000 (march) model and something between phase I and phase II.

Not shure whater VADIS knows what inside the CEM, but it would realy help!

[960kg]

Thank you for your picture, I really want this VADIS :-)

Unfortunatly the wiper relay has to be located in the CEM in my car model, the location you showed was in previous models though.

My car is a year 2000 (march) model and something between phase I and phase II.

Not shure whater VADIS knows what inside the CEM, but it would realy help!

...Vadis says it is in the same place on a V40 2001...read the model and year at the top....the CEM is changed as a unit with no pics. of the inside...2004 is the same...

[bommaz]

Thank you for posting this and the photos, went to scrappy today got CEM and now have headlights £47 total.

[bommaz]

going to get the alloys of it as well

[Wattsys40]

Can anyone help me? I have a 98 'S' S40, and I'm trying to locate the headlight relay. After looking at the picutres and almost breaking my back trying to get my head in the footwell, I don't have the same box of tricks there. I can't seem to find my CEM, or th headlight relay. If anyone can help me locate it, that would be fantastic and its had me scratching my head for days now!

[gatos]

Can anyone help me? I have a 98 'S' S40, and I'm trying to locate the headlight relay. After looking at the picutres and almost breaking my back trying to get my head in the footwell, I don't have the same box of tricks there. I can't seem to find my CEM, or th headlight relay. If anyone can help me locate it, that would be fantastic and its had me scratching my head for days now!

Had a quick look on Vadis for a 1998 car and it seems to be at the same place. Silly question, but have you removed the lower driver's side protector panel?

[gatos]

Wattsys40, If you need one, I have a spare one for sale by the way. That is if you find where yours is first. :)

[Wattsys40]

Had a quick look on Vadis for a 1998 car and it seems to be at the same place. Silly question, but have you removed the lower driver's side protector panel?

Thanks for looking, if you mean the panel that sides left of the bonnet release then yes I have, but all that is there is a keyless entry box and another little box, but none of it looked like the picture. If I get a change, I'll get out there and take a picture. Thanks for your help though, most appriciated.

[fearlesspierre]

I've just bought a second hand S40 1.8iXS with 36k miles and the paperwork with it shows that its had a new CEM because the headlamp bulbs were blowing. A common fault then.

[urbanite]

Wattsys40, If you need one, I have a spare one for sale by the way. That is if you find where yours is first. :)


I just got a nearside lamp out, and the heat has burned through the wiring and 3 spade plastic plug that connects to the bulb.

Gotta do some investigation first, but if I need a CEM, whats your price for your spare, posted to Wolves?

[s40rch]

Does this controll the fog lights in my 96 S40, does anyone know where the relay is located for the front fog lights or what item number it is Haynes and sidaV are useless!

[gatos]

I would suggest you check your PARKING LAMPS and POSITION lamps fuses in the engine compartment. One of them, I can't remember which one, had a fuse blown and apparently it was affecting front and rear fog lights. When i replaced that fuse I got both fog lights on the front and the one on the back working fine. Very odd as the Fog lights fuse was fine.

[qipan]

Thanks for the very useful information, Russell_S.

In my case, I have a V40 which had a failed LH dipped beam. The light was on if the engine was running and off if the engine stopped (all switches were on). Finally, this was traced to a problem with the relay on the CEM board. When the engine is on, the control voltage on the relay is about 13V, which is high enough to activate the old relay. When off, the battery voltage is about 11.5V, so the relay does not move at all.

The problem is definately with the relay. But to get a replacement relay is not easy. Dealers do not have the relay as a component but would charge about £450 for the whole CEM. In the end, I found a replacement from RS (stock number 217-2876) and only costs £1.47 plus VAT and del.

Link here:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=217-2876&x=0&y=0

I have also attached the datasheet here. It is 15A compared with the old 20A, but well enough for the dipped beam (about 5A).

After replaced with the new relay, my V40 returns to normal.

[acrobs]

hey qipan, you said yours was the ls, and that was the replacement relay for it.


will that same relay be ok for the right side light?


cheers andy

[littlehomer]

Hi All,

Great info, priceless.

The other relays in there, are they for fog lights?

I'm trying to retrofit front foglights and want to know if there's anything else I'll need.

Many Thanks,

Daniel.

[qipan]

hey qipan, you said yours was the ls, and that was the replacement relay for it.


will that same relay be ok for the right side light?


cheers andy


Hi Andy

From the picture of the CEM board, it appears that they are of the same type relay with the same part number on the body and so I think it should be okay for the RH side too.

[acrobs]

great stuff qipan

one last thing, does a phase 1 cem fit on a phase two cem, aand vice versa.


cheers

[qipan]

great stuff qipan

one last thing, does a phase 1 cem fit on a phase two cem, aand vice versa.


cheers

Sorry I have no idea. My V40 is 2000 GDI model, and the engine has the fly-by-wire type throttle. The CEM board is just like the picture shown at the beginning of the thread.

Probably you can check up with your local Volvo dealer parts to find out. After all the advice/info from them is free!

[mrbroons]

Hi, I have an XC90 (2003). My passenger side xenon dipped beam flicks on and off whilst I'm driving, sometimes it stays on for a whole journey other times it is on and off every 30 seconds, I've also got water coming into the cabin from somewhere (it's under the floor near the yaw sensor).

Just wondering if these things can all be linked. I'm really scratching my head with this one. I've posted under the proper forum section my problem but saw this thread whilst searching for an answer and just thought I would ask?

regards, Jim.

[qipan]

Hi Jim

I think you can do a quick test to see if the problem comes from the relay.

Switch on ALL lights but without turning the engine on (this will set a lower battery voltage to the relay), check if the faulty light is on. Then turn the engine on (set a higher voltage) and check the light again.

If the light is off when the engine is not running and on (or sometime on) when the engine is running, it is almost certain that the relay is faulty.

If the light is on in both cases, it may be something esle like bad contacts etc.

[mrbroons]

I have tried the test and my lights light up all the time, just seems to be whilst driving they cut out, does this point to a bulb or igniter failure?

[MiasMum]

Does anyone know if the CEM controls the sidelights? I have a 2000 V40 1.8 XS and none of the sidelights are working. Hubby says he has checked fuses and bulbs and says he can hear a relay clicking and is wondering if the CEM isnt sending power to any of the sidelights for some reason? (Headlights work if the switch is in position 0 and in headlights on position, both with engine on and off but no sidelights at all.)

[qipan]

I have tried the test and my lights light up all the time, just seems to be whilst driving they cut out, does this point to a bulb or igniter failure?

So it is inconclusive. Do not think it is due to the bulb but I could be wrong.

Maybe you can try cleaning the electrcial contacts of the light by using some electronic cleaning solvent (not the mechanic type like WD40). I have used it to clean the door light switch to make it work again.

[Mikez]

Does anyone know if the CEM controls the sidelights? I have a 2000 V40 1.8 XS and none of the sidelights are working. Hubby says he has checked fuses and bulbs and says he can hear a relay clicking and is wondering if the CEM isnt sending power to any of the sidelights for some reason? (Headlights work if the switch is in position 0 and in headlights on position, both with engine on and off but no sidelights at all.)

Are you sure the relay is working fine? I have a 2001 V40 1.8 which had a failed LH dipped beam. I knew the relay would be faulty when I read this topic, but it seemed to work when I tested it. I mean, there was around 12 V voltage when lights were turned on and zero voltage when lights were off. It looked like the relay would be OK (you could have heard a clicking sound if you had decent hearing), but still, there was no light. It somehow limited the current in such a way that it was not able to turn the light on. The relay may be faulty even if it seemed to be ok.

In my case, I fixed the lights by replacing the relay with about similar one.

[mmarreco]

Thanks for the very useful information, Russell_S.

In my case, I have a V40 which had a failed LH dipped beam. The light was on if the engine was running and off if the engine stopped (all switches were on). Finally, this was traced to a problem with the relay on the CEM board. When the engine is on, the control voltage on the relay is about 13V, which is high enough to activate the old relay. When off, the battery voltage is about 11.5V, so the relay does not move at all.

The problem is definately with the relay. But to get a replacement relay is not easy. Dealers do not have the relay as a component but would charge about £450 for the whole CEM. In the end, I found a replacement from RS (stock number 217-2876) and only costs £1.47 plus VAT and del.

Link here:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=217-2876&x=0&y=0

I have also attached the datasheet here. It is 15A compared with the old 20A, but well enough for the dipped beam (about 5A).

After replaced with the new relay, my V40 returns to normal.

Very useful info, thanks!

Was it easy to replace the relay on the circuit board? What tools did you use?

[pacman67]

Hi, I have an XC90 (2003). My passenger side xenon dipped beam flicks on and off whilst I'm driving, sometimes it stays on for a whole journey other times it is on and off every 30 seconds, I've also got water coming into the cabin from somewhere (it's under the floor near the yaw sensor).

Just wondering if these things can all be linked. I'm really scratching my head with this one. I've posted under the proper forum section my problem but saw this thread whilst searching for an answer and just thought I would ask?

regards, Jim.

I have heard of this water problem from a local volvo specialist, if i remember the water comes in somehere round the handbrake cable, which in turn rusts and snaps. Seem to remember him saying he,d seen a few with a fair bit of water under the carpets. Hope this helps. If you need mor info pm me.

[qipan]

Very useful info, thanks!

Was it easy to replace the relay on the circuit board? What tools did you use?

Was easy for me as I do soldering regularly. Maybe a bit tricky if no experience before.

Anyway I used a slightly bigger soldering iron tip (electronics tool) and some solder wick to absorb the solder as much as possible off the relay pins. And then gradually loose the pins inside pcb holes and gently pull the relay out while heat the pins at the same time. Once out of the board, it is easy enough to put a new one on. Good luck.

[V40DS]

The problem is definately with the relay. But to get a replacement relay is not easy. Dealers do not have the relay as a component but would charge about £450 for the whole CEM. In the end, I found a replacement from RS (stock number 217-2876) and only costs £1.47 plus VAT and del.

Link here:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=217-2876&x=0&y=0

I have also attached the datasheet here. It is 15A compared with the old 20A, but well enough for the dipped beam (about 5A).

After replaced with the new relay, my V40 returns to normal.

Hi, thought I would update this thread as the information posted above was a huge help providing me the information needed to repair my CEM. I have a V40DS on a '51 plate and the nearside dipped headlight beam would sometimes work and sometimes not, this had no real pattern whether ignition was on or off. I removed the CEM from the plastic enclosure and plugged it into the car as a bare board and when I found the headlight not on, flicking the corner of the board would force it on everytime. I ordered the above relays (£1.74 plus VAT + Shipping - 2 relays will actually cost you about £9.50 as the shipping is next day at £4.95). Desoldered the old relay and installed the new one and now the headlight is working perfectly.

Thanks again for the help and confirmation this procedure was correct for my circumstances as above.

Picture below shows new relay in the center, darker than the others.

http://i52.tinypic.com/wkpjix.jpg

[sebaveh]

Well, it happen to one of our fellow volvo owner, who happens to know about electronics too. He soldered new relay in place and it worked. Later, he went to analyse the old relay part. He took it apart. Guess what he found - inside was another, smaller relay, soldered to pins of outer shell. How amazing is that ?!?!

[Clan]

I wonder if this unit can be altered to turn off the DRL's :P

yes , just read your owner's handbook :-)

[Dog_Book]

yes , just read your owner's handbook :-)

I have and in a P1 there is no option to do this ;/

[Clan]

I have and in a P1 there is no option to do this ;/

Sorry , you cant on the early one without cutting wires , after 2000 its simple and in the handbook ..

[woodypecker]

This information has been really useful! I have a V40 2.0T yr 2000 and in the shop they just said one of the two pairs of rear position lights (sorry about my Spanglish!) is not working. They claim this is due to the CEM, and of course offer me a nice replacement for 522 Euros! Do you know if there is also a relay in this CEM that controls those rear lights (there is one pair of lights on the trunk door and another pair on the main body of the car). Thanks!

[sebaveh]

Yes, inside CEM are two (2) relays for position lights.

-One is for inner (on trunk door) and for licence plate illumination.
-One for outer (on car body) and for front position lights (inside headlamp).

But first, check all the fuses, and a cable between trunk door and body. Due to a trunk door open and close, this cable can often break.

[sandror9]

which the value of R47, R49, R11 and R122?

[jordanfc]

Hey, Russel,
thanks for the critical info. even with my background of 30 years in electrical, instrumentation, and electronics, it was really difficult to troubleshoot a system whose engineers are information anal. i hope this doesn't break forum rules re language. i am new to forums. I have replaced engine and trans on my daughters 2000 s40, and have been appalled at the info access difficulties.

Thanks again
ps, re protocols, are the couple of capital letters I put in for emphasis considered bad form? also, is there a way to contribute $$ to forum support? It of course is much cheaper than Vadis subscription, or buying even more bogus Vadis copies! lol :-)

[jordanfc]

Hi, I've recently had a headlight problem which, at first, appeared to be the common CEM issue (see this thread http://www.volvoforums.org.uk/showthread.php?t=67437) but finally turned out to be a break in the wiring loom. However, while fault finding the problem I found out a bit about the CEM which I thought others could find useful in faulfinding their own headlight related issues. I've taken a few pictures to help with this.

I have attached to this thread the Volvo wiring diagram for the CEM and headlights because the Haynes manual is worse than useless in this respect as it doesn't even show the CEM in their wiring diagrams.
I have also attached the data sheet for the Fujitsu relays that are used for the headlight switching in the CEM. I originally assumed that they would be solid state relays but in fact they are normal miniature PCB mounting mechanical relays so it they do fail then the data sheet could help find a replacement to repair the CEM.

Firstly, for those who don't know where the Central Electronics Module (CEM) is situated, here is a picture:
http://i93.photobucket.com/albums/l74/RussellS_2006/CEMLocation.jpg


Next we have a picture of the CEM circuit board itself highlighting the headlight relays:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMPCBRelays.jpg


and now a picture of the CEM connectors and their pin numbering to go with the attached wiring diagram:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMConnectors.jpg


Hopefully others will find this information useful as the CEM does appear to be a weak component with respect to headlight switching.


Regards

Russell
Hi again Russel,
would be glad to pay for info, I have scoured the fujitsu database with no replacement relays compatible. no prob if just a relay base, but modifying the volvo cem prob not good idea. have you found replacement from any source?

[gatos]

Hi again Russel,
would be glad to pay for info, I have scoured the fujitsu database with no replacement relays compatible. no prob if just a relay base, but modifying the volvo cem prob not good idea. have you found replacement from any source?

The idea of forums is generally to share knowledge for free. Payment would only be considered in cases where actual car parts are sold or sometimes when someone helps someone else to repair something (in most cases it's free too). The best way to pay back here is to offer your brains and ideas here so everyone else can benefit.....

[Kim4800]

Hey

Does anyone have the schematic for the cem? or knows what component there is on place DA13 and DA12? Mine has fallen off.... and I have to replace the components..

Kim

[sebaveh]

My wild guess - it might be a double diode with common anode? Do you still have it lying inside housing?

[Kim4800]

Yes only the one. A little black thing in a SOD323 case... And I think that there is printet B3 on it.. I think it is the same as DA15. But I need more to ordre it from a anyone

[Kim4800]

A BZX399C2V2 from Philips ?

[sebaveh]

Are you sure? Because DA12 and DA13 looks like a SOT-23 package with 3 pins from picture?
In that case they might be 1SS184 or HSM2694 or similiar...
Are any of those three pins short-circuited? Or where they go (if it is possible to track them?) Can you use a multimeter (diode test) and do some measurements?

[Kim4800]

Now I mesured the chip. It is NOT a HSM2694 since it has a common Anode, but The 1SS184 looks prommising :-) and yes it is the SOT-23 case not SOD323.

I keep working...

[Kim4800]

I cant get the toshiba diode in denmark, so I try the BAP70-05 insted

Thanks for now.

[Mike Aherne]

Did someone know, which of this is the rear wiper relay?

The left hand one on the CEM. If you put a finger on it and then operate the rear wiper switch you should feel it click if it is working.

[Roman62]

Hi,
Is the CEM and ECU one and the same?

I was told by a local Volvo "expert" that the CEM is coded and can only be used on the same car. Is this true?

[gatos]

Hi,
Is the CEM and ECU one and the same?

I was told by a local Volvo "expert" that the CEM is coded and can only be used on the same car. Is this true?

No they are not the same. There seem to be a couple of different model numbers for the ECU on the S40. I have tried the ECU from a 2001 1.6 S40 on my 1.9D and everything was fine.

What exactly are you trying to do?

[960kg]

...if you can locate the relay in the CEM just replace it you will need a soldering iron!...B2 on the wiring diagram leads to it...all modern relays are available on the internet outlets somewhere you just have to do your own homework..

[960kg]

...if you can locate the relay in the CEM just replace it you will need a soldering iron!...B2 on the wiring diagram leads to it...all modern relays are available on the internet outlets somewhere you just have to do your own homework..

.....IGNORE answered wrong thread!!!!

[71impala]

Thanks to all of you who have posted on this site.

Had the same cem problem on my mate's s40.

Bought a relay at RS for a couple of quid, removed the old one from the pcb and soldered in the new one. Lights now all work as good as new and without the horrible expense.

I'm not great with a soldering iron but managed to do this ok by taking a bit of time and going at it gently. No-one should be put off from giving it a go.

Once again Thanks.

Pete.

[Buzzvolvo]

Hi, I've recently had a headlight problem which, at first, appeared to be the common CEM issue (see this thread http://www.volvoforums.org.uk/showthread.php?t=67437) but finally turned out to be a break in the wiring loom. However, while fault finding the problem I found out a bit about the CEM which I thought others could find useful in faulfinding their own headlight related issues. I've taken a few pictures to help with this.

I have attached to this thread the Volvo wiring diagram for the CEM and headlights because the Haynes manual is worse than useless in this respect as it doesn't even show the CEM in their wiring diagrams.
I have also attached the data sheet for the Fujitsu relays that are used for the headlight switching in the CEM. I originally assumed that they would be solid state relays but in fact they are normal miniature PCB mounting mechanical relays so it they do fail then the data sheet could help find a replacement to repair the CEM.

Firstly, for those who don't know where the Central Electronics Module (CEM) is situated, here is a picture:
http://i93.photobucket.com/albums/l74/RussellS_2006/CEMLocation.jpg


Next we have a picture of the CEM circuit board itself highlighting the headlight relays:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMPCBRelays.jpg


and now a picture of the CEM connectors and their pin numbering to go with the attached wiring diagram:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMConnectors.jpg


Hopefully others will find this information useful as the CEM does appear to be a weak component with respect to headlight switching.


Regards

Russell


Thanks for this detail on the CEM. Headlight relays for Fujitsu are now obsolete but Farnell were able to supply a replacement JSM-12-5 which is an exact fit rated at 15A cost £2 to £3 pounds (downside is Farnell have a minumum order of £20) excellent delivery.

A fairly easy procedure to replace provided you have a soldering iron and a solder sucker.

regards
Buzz

[Bogart302]

Thanks. Great info.

I'm located in the states and have the US version, but the same info applies.

I also had the problem where the RH dipped beam quit working. I looked up the datasheet for the relay, and was able to "fix" the problem by soldering a jumper wire across the output pins of the two relays, so that now one of the relays (the still working one) controls both of the dipped beams.

If you look at the relay pins on the board, you will see that there are 5 pins on each. 3 with large solder pads, and 2 with smaller pads. I soldered my bridge wire to the one large pad that is located between the two smaller pads on each dipped bean relay. This is the common pin, which (somewhat counterintuitively) is used as the output in this case.

The relays appear to come in 10A and 15A versions. I don't know which is installed on the CEM from the factory. I figure that even if it's the 10A version I am not exceeding the specification by having it drive both bulbs. 55W @ 12V == 4.583A each, or 9.16A for both.

I may still order a replacement relay. I think it's this one (for the 15A version):

http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=JSM1-12V-5

[sebaveh]

That is a nice fix, but only for temporary time, if you ask me. The "problem" is that you have one relay for each side, and also one fuse for each relay and light. If you see inside fusebox in engine compartment, you will see two 15 Amp fuses, one for LH and one for RH side. This is done for a safety reason on every car and it is obligatory for every car on earth. Just in case something goes wrong anywhere, and one fuse pops, you will still be left with another light working.

High beams do not need this, and can be wired together on one fuse and/or relay.

My suggestion is, that you buy replacement relay from Farnell or other store, and replace it.

[Bogart302]

That is a nice fix, but only for temporary time, if you ask me.

Well it looks like that indeed turned out to be true. My "fix" lasted about 3 days, and then the remaining relay gave out.

I ordered replacement relays from digikey and soldered them in. They were an exact fit, and the lights work normally again now.

My 30-watt iron seemed a bit underpowered for the job. If I were to do it again I would prefer a 40-watt or higher.

[daz1978]

Hi further to the above diagrams & info, does anyone know if the relays for the headlights (current N/S) are replacable, and how easy is it. I have seen someone post a email address for a supplier, but would like to know the theory behind changingone, before I try.

Thanks for your time.

Darren

[Gizmo_V40]

I'd just like to thank those who have posted such useful information on this thread. Both mine headlights were turning on and off randomly, 2 new relays from RS and about an hour to desolder, remove and replace the relays and all is back to normal!

[Biotoxic]

1. Are all phase 2 main beam relays the same spec?
2. Could somebody post a link to ebay or other place where I could get them?

I tried to search that Farnell site for those replacement relays but no success ...

[Brian021176]

Hi, thought I would update this thread as the information posted above was a huge help providing me the information needed to repair my CEM. I have a V40DS on a '51 plate and the nearside dipped headlight beam would sometimes work and sometimes not, this had no real pattern whether ignition was on or off. I removed the CEM from the plastic enclosure and plugged it into the car as a bare board and when I found the headlight not on, flicking the corner of the board would force it on everytime. I ordered the above relays (£1.74 plus VAT + Shipping - 2 relays will actually cost you about £9.50 as the shipping is next day at £4.95). Desoldered the old relay and installed the new one and now the headlight is working perfectly.

Thanks again for the help and confirmation this procedure was correct for my circumstances as above.

Picture below shows new relay in the center, darker than the others.

http://i52.tinypic.com/wkpjix.jpg
Thanks i have just ordered two relays i have the same problem with my near side headlight but am going to change the two relays as the other ones bound to go at some point i'll let you know how i get on

[kifla]

Hello, I'm new here.
I am having a problem with my s60 '03 2.4 Black Edition. Sometimes during the driving lights on control board goes off, HL goes off and, if I am not happy, the door were locked so going out of the car becomes PIA. Volvo service told me that is a faulty CEM and they charge cca. 1300€ for replacement.
Does anyone here knows where is the CEM located on S60 - maybe I can try to look at relays - because when those things happens -I can always hear the sounds of relays clicking? Thx.

[gatos]

Try posting in the S60 section:
http://www.volvoforums.org.uk/forumdisplay.php?f=19

I am sure someone there will be able to help you. This is the S40/V40 section.

[stuhandy]

Hi there, My CEM has given up the ghost so I will be replacing it. If I use another CEM does it need registering to the car or is it plug and play? Regards Stu.

[gatos]

The CEM should fit on the car as it is with no need for programming. However, certain functions might need programming, ie fog light and rear wiper.

However, if the replacement CEM came from a car with fog lights on it, then you will not have to program it for fog lights. If you have a V40 and the replacement CEM comes from an S40, you will need to program the rear wipers to the CEM. However a V40 CEM will work on an S$) as is.

What car have you got? I have an S40 CEM and Siamblue has a V40 CEM, both with fog lights, so no programming will be needed.

[stuhandy]

Gatos, thanks for the reply. I have a 2002 v40 diesel, fog lights incl.

If I need to programme the new CEM, how is this done?

Iam new to this website

[stuhandy]

Thanks Gatos, I think I would like to keep this as simple as poss. Do you know if Siamblue still has there CEM and would they part with it?

[gatos]

Gatos, thanks for the reply. I have a 2002 v40 diesel, fog lights incl.

If I need to programme the new CEM, how is this done?

Iam new to this website

In that case you will need a CEM from a V40 with fog lights and you will not need any further programming at the dealers.


Thanks Gatos, I think I would like to keep this as simple as poss. Do you know if Siamblue still has there CEM and would they part with it?

Yes he does. I actually have his one at my house house. I will ask him how much he wants for it and he will either reply here or send you a pm

[baldmosher]

Awww, shucks, bad timing.

The new stalk didn't work gatos, so it looks like my CEM after all. Anyone know where to locate the relay for the front windscreen wipers? I notice it's not mentioned on the diagram...?

[gatos]

It is programmed in the CEM, so in one of the relays. So even if you replcaced a relay, you would still have to reprogram it.

I know Siamblue has contacted stuhandy, but I am not sure if they have gone ahead. If not, then you can drop an email to Siamblue about the CEM.

Or if you can't get hold of one, I can lend you a spare CEM I have for an S40 and you can use it temporarily. You will be able to use the front wipers, but not the rear one.

What makes you think that it was the wiper stalk first and now the CEM? Have you checked if the wiper motor is working first? Have you checked to see if a signal goes through to the wiper mechanism? It is better to start with the easiest and cheapest option, before you start spending money on parts you don't need.

[baldmosher]

I have intermittent wipe. Just no single/on/fast/wash function. Washer motor works off the car.

What else could it be?

[gatos]

Oh ok. Then that would probably be the CEM. PM Siamblue if you want and see what he says about his CEM. He has one move CEM but he might need it to transfer the Xenon lights from one car to the other. We are both not sure if the CEM comes into play to the Xenon self levelling, so we will be finding out in the near future. Then he will have one more CEM available.

[baldmosher]

siamblue has now contacted me, apologies everyone for the brief thread hijack :)

PS back on topic, my local friendly auto electrician reckons he can reprogram the 2002 CEMs (if for example I got an S40 CEM that didn't have rear wash/wipe function). Which means if he can do it, others can too. Unless he's talking bullshine of course and he can't really do it....

[Elchopperfreak]

Hi
What would be the relay for the winshield wipers, just got a V40 and the wipers stop in the position were you switch them off.
Thanks

[yalinf]

Thank you to all involved in this thread.

I brought a 2003 V40 1.9D 2 weeks ago with what I thought was a blown near side dipped beam bulb.

Tried changing it to no avail. Pulled out headlight etc to check wiring but all was fine.

Quick google search brought up a few things but in particular this.

Managed to get 2 new relays this am from RS as per link on earlier page, fitted them both (N/S and O/S save doing it again later) and now working like a treat.

Out of curiousity (and after making sure new ones worked), I stripped the 2 old relays to see if there was a difference. The result is the faulty 1 has a dirty/ burnt out contact as per picture;

Faulty N/S relay on the left, Working O/S on the right;

http://i162.photobucket.com/albums/t268/Cookie_e39/IMG00440-20120511-1610.jpg

How did we survive without the internet? :)

Thanks again all and I look forward to being a more active member on this friendly forum.

Chris.

[hawkins]

i have similiar problem in that front and rear fog lamps and the dash tell tales dont work neither do front and rear parking lights or switch illumination help! 2002 s40 diesel sport im thinking cem packing up

[T4Rick]

This is a really good thread:thumbs_up:

[RandomGuy]

Hi all,
I have an 02 S40 1.9D Sport. Had a similar problem, n/s dipped beam not working. Bought "fully tested" replacement CEM from Ebay. Fitted and now have n/s dipped beam but no main beams in any of the switch positions. Refitted original CEM and main beams returned. Contacted seller, who says CEM needs to be reprogrammed! Other contributors to this forum have bought CEM's from scrappies and not had to do this.

Have I been conned or just unlucky? Surely whatever car it is from, the main beams should work?

Can I just swap the n/s dipped beam relay to my old CEM?:lightbulb:

[cnoe]

Long time lurker, first time poster. Just finished replacing the faulty relay in the CEM of my 03 S40 and had to offer my appreciation to this thread. With literally zero PCB/solder skills, was able to replace my relay and resolve my right headlight issue within an hour start to finish. $7 with shipping sure beats the Volvo quote (over $1200) or the used option on eBay ($150).

Thanks all! Cheers-

[RandomGuy]

Hi all,
I have an 02 S40 1.9D Sport. Had a similar problem, n/s dipped beam not working. Bought "fully tested" replacement CEM from Ebay. Fitted and now have n/s dipped beam but no main beams in any of the switch positions. Refitted original CEM and main beams returned. Contacted seller, who says CEM needs to be reprogrammed! Other contributors to this forum have bought CEM's from scrappies and not had to do this.

Have I been conned or just unlucky? Surely whatever car it is from, the main beams should work?

Can I just swap the n/s dipped beam relay to my old CEM?:lightbulb:

Any ideas?

[gatos]

Any ideas?

It is a programmable feature that can be done by anyone with DICE. However, I find it really hard to believe that someone programmed the CEM disabling the main beams

[chubby brown]

Any ideas?corroded wiring loom under the radiator :lightbulb:

[RandomGuy]

It is a programmable feature that can be done by anyone with DICE. However, I find it really hard to believe that someone programmed the CEM disabling the main beams

Thanks Gatos, my feelings exactly! Why would anyone disable main beams?
don't think the wiring loom under the rad is at fault, main beams work on my original CEM.

Just discovered CEM is from a 01 V40, is this a problem?

[gatos]

No it shouldn't be a problem. THe only difference between the S40 adn V40 is that the V40 CEM is programmed for the rear wiper. However I have tested and confirm that with VIDA and DICE, you can program an S40 CEM to utilise the rear wiper as well as enable/disable the fog lights and some other functions.

Tell the buyed you want to return this CEM and that you want your money back. The description of the item was incorrect. Even if what he says is true, then Volvo would charge you a fortune to reprogram it. I also have a CEM in case you still need one. I have tested it on my own car and everything works as it should.

[RandomGuy]

No it shouldn't be a problem. THe only difference between the S40 adn V40 is that the V40 CEM is programmed for the rear wiper. However I have tested and confirm that with VIDA and DICE, you can program an S40 CEM to utilise the rear wiper as well as enable/disable the fog lights and some other functions.

Tell the buyed you want to return this CEM and that you want your money back. The description of the item was incorrect. Even if what he says is true, then Volvo would charge you a fortune to reprogram it. I also have a CEM in case you still need one. I have tested it on my own car and everything works as it should.

Many thanks Gatos, you have confirmed my suspicions and also answered my next question, i.e cost of reprogramming. I will return the unit and demand a refund. I would like to buy your spare CEM, how much do you want for it?

[gatos]

I normally sell them at £30 plus postage. However, in case it does not solve your problem, then you can of course return it back with no questions asked.

I will also need you to confirm what your car has on it, so I can program the relevant values. In your case, you have a 2002 S40 1.9D, so rear wiper is out of the question. However, I need to know if you have front fogs or not. Or I can program it with fogs in case you don'ts have any and would like to add them in the future.

[RandomGuy]

I normally sell them at £30 plus postage. However, in case it does not solve your problem, then you can of course return it back with no questions asked.

I will also need you to confirm what your car has on it, so I can program the relevant values. In your case, you have a 2002 S40 1.9D, so rear wiper is out of the question. However, I need to know if you have front fogs or not. Or I can program it with fogs in case you don'ts have any and would like to add them in the future.

That's great, Gatos.
Please program it for front fogs, I dont have them but would like to fit them,
are they difficult to fit? do you happen to have a set?
Can you take payment via PayPal? if not I can post you a sterling cheque.:thumbs_up:

[gatos]

That's great, Gatos.
Please program it for front fogs, I dont have them but would like to fit them,
are they difficult to fit? do you happen to have a set?
Can you take payment via PayPal? if not I can post you a sterling cheque.:thumbs_up:

They are fairly easy to fit I guess. I have them on my car, but I hardly ever use them and find them pretty useless.... lol. But a lot of people like them. Paypal is fine.

I don't have a set of fogs, but Siamblue has one, so you can ask him. He leaves down the road from me, so he can drop them at my place and I can send everything together.

You will also need the headlight switch with the fog lights buttons on it, in which case, I have it for a tenner

[feifeialex]

Hi,

I'm new here, I got the problem with my dipped head light on both sides, just one day before the scheduled service... good timing...
it is a v40, 2003.
when i took the car to service, the dealer just said this was because of replay in the cem box need to be replaced. Based on there was no voltage on the headlight socket, the fuse in the fuse box was ok. If I replace the new cem box, costs more than 4000 sek... Sorry forgot to mention I'm in Sweden.
So I took the car home, opened the cem box with the wires on and test with voltmeter. Please help me to see if the replay is working. Because I'm so lost and give the basic physics to my teacher :-P

when the key is off,
the voltage between com and NO is 12.15 on both sides

when the key is on
and light switch on
the voltage between com and NO is 11.90 on both sides.

Are these relay working? or the contact got oxidized? Thanks!

[RandomGuy]

:thumbs_up:They are fairly easy to fit I guess. I have them on my car, but I hardly ever use them and find them pretty useless.... lol. But a lot of people like them. Paypal is fine.

I don't have a set of fogs, but Siamblue has one, so you can ask him. He leaves down the road from me, so he can drop them at my place and I can send everything together.

You will also need the headlight switch with the fog lights buttons on it, in which case, I have it for a tenner

Problem finally sorted, new CEM from Gatos works fine. Thanks to Gatos and SiamBlue for all your help.:star:

Lesson learned, beware of "fully tested " spares from FleaBay! Dodgy CEM returned for refund. I will source all my spares on this forum in future.

[kirkcairns]

Does anyone know, which of this is the front and rear sidelights (parking lights) relay?

[1066harold]

hi all the cem I changed my headlight worked immediately done so simple its a joke all tools requited a philips screwdriver
done
thanks to you all this thread really did the biz for me awesome

[1066harold]

Guy's I brought my CEM from Ebay working no issues
cost and this is true £5.00 post £0.99 for the item
total £5.99
right chuffed

[baldmosher]

Well done, I got £40 for mine! Took a while to sell though

[ciaranr]

With one dim dip headlight down, I replaced both dim dipped relays on the CEM with RS Component's part number 2172876 (http://radionics.rs-online.com/web/p/non-latching-relays/2172876/?searchTerm=2172876&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6 265724D504E266C753D656E266D6D3D6D61746368616C6C267 06D3D5E5C647B367D247C5E5C647B377D247C5E5C647B31307 D2426706F3D313426736E3D592673743D52535F53544F434B5 F4E554D424552267573743D323137323837362677633D4E4F4 E4526) at a cost of less than €10, got a friend to solder them in and it worked a treat! Thanks once again to all who posted to this thread and others.

[mfelix]

How do you take the old relay out? and how do you replace it with another?

[gatos]

You will need a soldering/de-soldering iron. If you have never soldiered before it's not the easiest job to do

[keefer]

Hi all and thanks for the info Russell. I too have a suspected CEM problem but I'm unable to track down a replacement for this particular part number (30621304) which appears to be for the LHD version and the only ones I can find are in America.

I'm beginning to wonder if I have the correct CEM in place and would be grateful if anyone can confirm the part number. My car is a 2002 V40 1.9D S, registration number WK02 MZX.

I changed the bulbs and can confirm the new ones are working (tried a different CEM that I thought might work 30858700) but it left the lights on all the time and a meter read at the fuses is showing no power.

Many thanks in advance

[gatos]

Depends what your Chassis number is. Check the last 6 numbers on your VIN.

See here:
Control unit [-2001, L.H.D (30859699)] 30896697
Electronics box [2002-, L.H.D (30621304)] 30638707
Control unit [-2001, R.H.D (30859700)] 30896698
Electronics box [CH 800000-026445, R.H.D] 30621305
Electronics box [CH 026446-, R.H.D] 30638708

Yours will either be the 30621305 or the 30638708

I think I have both in case you want one and I can enable/disable the fogs, rear wiper etc

[sebaveh]

I am 99 % sure that only difference between LHD and RHD version is in housing - position of mounting tabs.

[gatos]

I am 99 % sure that only difference between LHD and RHD version is in housing - position of mounting tabs.

I think so too.

[Clan]

Hi all and thanks for the info Russell. I too have a suspected CEM problem but I'm unable to track down a replacement for this particular part number (30621304) which appears to be for the LHD version and the only ones I can find are in America.

I'm beginning to wonder if I have the correct CEM in place and would be grateful if anyone can confirm the part number. My car is a 2002 V40 1.9D S, registration number WK02 MZX.

I changed the bulbs and can confirm the new ones are working (tried a different CEM that I thought might work 30858700) but it left the lights on all the time and a meter read at the fuses is showing no power.

Many thanks in advance

is your car a LHD ? I have a feeling it may be an import ... and not visited a volvo garage over here ..

[jimba]

I noticed on Russell_s original post, the wiring diagram shows the fog wiring as well. My V40 does not have the fogs, can I simply unsolder the relay for the fogs and place it in the faulty dip's place leaving the fog relay location blank? If so what of the relay numbers is the fog relay? (There are 6 identical relays on my board. Russell_s photo shows 4, an obvious difference in year or country) I'm assuming RLY1 or RLY2.
Thanks for any help you can toss my way.

[StephV40]

Hi,
Just want to thanks for this great thread! My right headlight didn't worked for a couple of months now and the fog light (and switch) I installed this summer, I coudn't managed to have them work... Visited 2 dealers and no answer on solution... (I have a V40 2002)
After reading this, I got a used CEM from a V40 2004 with fog, just swap with mine and headlight and fog turn on!!!
I'm a happy man!
Many thanks

[LizzieT]

Would you by any chance have a CEM for sale for 03 V40? No dipped headlamps but full beams work OK.



The CEM should fit on the car as it is with no need for programming. However, certain functions might need programming, ie fog light and rear wiper.

However, if the replacement CEM came from a car with fog lights on it, then you will not have to program it for fog lights. If you have a V40 and the replacement CEM comes from an S40, you will need to program the rear wipers to the CEM. However a V40 CEM will work on an S$) as is.

What car have you got? I have an S40 CEM and Siamblue has a V40 CEM, both with fog lights, so no programming will be needed.

[gatos]

Would you by any chance have a CEM for sale for 03 V40? No dipped headlamps but full beams work OK.
Can you check the part number on it and let me know so I can check the ones I have? It should be 8 digits long and starting with 306 or 308. Are you sure it is your CEM that is at fault?

[LizzieT]

Pretty sure it's the CEM, local auto-electrician diagnosed problem back to the CEM. Same thing happened a couple of years ago, no dipped headlights and volvo quoted €500+ for the part. Eventually got one in a breakers yard although it was on an S40 as not so many V40s sold over here. Although Volvo parts claimed that it was an unusual fault when I rang around beakers yard lots of the CEMs were missing! Part no. I have is 30621305 which is the one from the S40, unfortunately I dumped the original. By the way, great forum.

[gatos]

As far as I am aware of, the part numbers don't differ between the S40 and the V40. The only difference on the V40 is the presense of the rear wiper which the S40 does not have. The only difference I have found out todate between the different part numbers of CEMs is the operation of the high beam. If a different CEM is used, then the high beams will not stay on when you pull and release the indicator stalk. There seems to be a link between stalks and CEMs. I definitely have a 30621305 so if yours was working fine all this time then my one should not be a problem.I will program the rear wiper and test all the functions of the CEM on my car to make sure it is fine. I will PM you my email so you can contact me.

[LizzieT]

Got the CEM and my headlamps now work perfectly. Thanks a million.

[gatos]

Got the CEM and my headlamps now work perfectly. Thanks a million.

Thanks for letting me know. Hope this one lasts you for some time. Also, if you decide in the future to add fog lights, they will just be plug and play:).

[zeverken]

Hello people! I am glad to have found this forum because you seem to be just the person who can maybe help me.

I've been driving around with a 2001 V40 for about a year now, with the rear wiper dead. The volvo dealer first thought the motor was broken, but after further diagnostics they blame the CEM (at a mind blowing cost of course).

From what I've read it looks like a CEM is fairly straightforward to replace with a second hand one. But I don't understand the 'programming' bit fully. Is the programming unique for every car? Is there a wrong CEM I can buy for a V40? You said you have some lying around. What would be your price?

thanks for reading!
best regards,
Zev

[gatos]

Hi Zev and welcome to the forum. When I use the term "programming, it may sound more complicated than it really is. What it really means, is that you can enable/disable a few options with the click of a mouse. See attachment.

The following components and functions can be activated:

The following can be programmed:


Automatic low beam
Twin headlamps
Front fog lamps.
Tailgate wiper
Tailgate wiper when reversing.



There are a few different CEMs out there as they have changed something over the years. They are not car specific and you can easily swap them from one car to another. Here are the different models listed in VIDA:

Control unit [-2001, L.H.D (30859699)] 30896697
Electronics box [2002-, L.H.D (30621304)] 30638707
Control unit [-2001, R.H.D (30859700)] 30896698
Electronics box [CH 800000-026445, R.H.D] 30621305
Electronics box [CH 026446-, R.H.D] 30638708

Ideally you should try to replace the CEM with another one with the same part number. Saying that, I have tried a late 2000 CEM on a 2003 car and it worked fine. Only issue I am aware off, is that if you mismatch some CEMs, then the high beams are in "soft touch mode", meaning that when you click the indicator stalk backwards for the High beams, they don't stay on unless if you hold the stalk towards you.

Anyway, back to your problem. It is possible that the previous owner swapped a CEM taken from an S40, which has no rear wiper by default. In this case Volvo should be able to program it in less than 5 minutes. Or, it is possible that your CEM has developed a fault and it needs replacing.

[swordsmanvolvo]

Hello mr gatos
I have a 2001 s40 (with fogs) and am pretty sure it needs a new CEM to fix the headlight relay problem. I already checked the bulbs and fuses. There are some (CEMs) on ebay but I am reluctant to take a chance on these - I wonder to you have any more for sale which will work with the fogs?

[gatos]

Have you checked the voltage across the headlights? Do you get 12V?

Can you let me know what the part number on it is. You most probably have the 30621305. I can program/enable/disable different things and test the CEMs on my car to make sure everything works

[swordsmanvolvo]

Thank you for replying
No, read a few threads here and in various other places an formed the view it was the CEM.
I don't have the expertise or equipment to check the voltage
I was driving along one evening - lights working ok then switched to headlights and back low beams and they were gone
I will check the part number tomorrow evening
It seemed worth the few euro to chance replacing the CEM?

[gatos]

Thank you for replying
No, read a few threads here and in various other places an formed the view it was the CEM.
I don't have the expertise or equipment to check the voltage
I was driving along one evening - lights working ok then switched to headlights and back low beams and they were gone
I will check the part number tomorrow evening
It seemed worth the few euro to chance replacing the CEM?

You will know it is a failed CEM, when you get a voltage reading with a meter, but the bulb is not working. It is an odd occurrence.

If however you don't get any voltage readings, then it could be something as simple as a fuse, or worse case scenario a sorting of the loom under the radiator.

Also it would be a good investment to get a cheap multimeter as they do come handy. And if you don't know how to use it, there are plenty of video guides on youtube.

£2.99 for a cheapy one http://www.ebay.co.uk/itm/DIGITAL-MULTIMETER-CIRCUIT-TESTER-MULTITESTER-VOLTMETER-TESTER-WITH-BATTERY-/160737091237?pt=UK_BOI_Electrical_Test_Measurement _Equipment_ET&hash=item256cad5ea5

and there are many others at £5, £10 or £20.

[kirkwallcity]

This a really informative thread.

I bought an '03 V40 three weeks ago, but havenever got full beams to work. Not the fuses or the bulbs and both sides have failed. When I pull the lever to go to full beams I here a click which I thought was probably the relay (?) When the lights are set to sides or drls I can flash the full beams though which seems strange. Interestingly, the garage which serviced the vehicle for the previous owner says they have put in a new CEM.

Any thoughts?

Bob

[gatos]

Most probably they used an older CEM.
I think your car should come with the CEM with part number 30638708. If you look under your drivers footwell, you will find out that you most probably have either the 30621305 or 30896698 fitted on your car now

[kirkwallcity]

Hi Gatos,

I checked the part this morning and it does have number 30638708. Is there any possibility that it should be one of the others? Alternatively, is it possible that it's a relay? I hear the relay clicking away.

Cheers

Bob

[gatos]

These are the various part numbers for the CEM:

Control unit [-2001, L.H.D (30859699)] 30896697
Electronics box [2002-, L.H.D (30621304)] 30638707
Control unit [-2001, R.H.D (30859700)] 30896698
Electronics box [CH 800000-026445, R.H.D] 30621305
Electronics box [CH 026446-, R.H.D] 30638708

By checking your chassis number (last 6 digits on your VIN) you should be able to find out which CEM your car should have.

What part number is the CEM you have?

The relevant relays are actually inside the CEM

[Clan]

These are the various part numbers for the CEM:

Control unit [-2001, L.H.D (30859699)] 30896697
Electronics box [2002-, L.H.D (30621304)] 30638707
Control unit [-2001, R.H.D (30859700)] 30896698
Electronics box [CH 800000-026445, R.H.D] 30621305
Electronics box [CH 026446-, R.H.D] 30638708

By checking your chassis number (last 6 digits on your VIN) you should be able to find out which CEM your car should have.

What part number is the CEM you have?

The relevant relays are actually inside the CEM

To confuse matters dont forget the chassis numbers went back to zero around 2002

[kirkwallcity]

9####5 is the last 6 digits ln the chassis/vin and the part number of the CEM is 30638708.
Thanks for all your assistance.
Bob

[gatos]

I would remove your chassis number now, as this is a public forum. Or, change it to something like 952**5

It would appear that your car should have the 30621305 CEM. Let me check VIDA and I will see what comes up. In the meantime, change your Chassis number:)

[gatos]

Checked VIDA and could not find any more info. YMaybe you could call your local dealership and ask them what part it should be. They have a much more detailed database and they will be able to tell you the correct part number.

If you have the correct CEM, then the only other thing that might have happened, is that the previous owner replaced the indicator stalk which does not match the CEM and would also explain your problem

[Clan]

Hi Gatos,

I checked the part this morning and it does have number 30638708. Is there any possibility that it should be one of the others? Alternatively, is it possible that it's a relay? I hear the relay clicking away.

Cheers

Bob

yes it should be one of the others , as your chassis number is in the 900000 range you should have 30621305 ( chassis 800000 - 026445 )

30638708 is for the very last S/V40s from chassis number 026445 thats 2003 and 2004 models ..

remember i said the chassis number went back to zero around 2002

[kirkwallcity]

Thanks for all the help folks. A bit of a nightmare. I'll speak to my local dealer (100 miles away) to double check.
Bob

[gatos]

Thanks for all the help folks. A bit of a nightmare. I'll speak to my local dealer (100 miles away) to double check.
Bob

A quick call should do. Have your VIN handy

[dwin]

Is it possible to replace just the headlight relay in the CEM? I opened the CEM up and it looks like the relay is soldered in place, but has a little gap between it and the circuit board. Is it soldered or does it connect to something that is soldered in place? Any help would save $$$!

[gatos]

This is what this post was originally for. If your soldering skills are good, you should have no problems removing it and putting a new one on. See the first few posts

[Clan]

Is it possible to replace just the headlight relay in the CEM? I opened the CEM up and it looks like the relay is soldered in place, but has a little gap between it and the circuit board. Is it soldered or does it connect to something that is soldered in place? Any help would save $$$!

yes it is possible if you can locate the same type relay , but what i would do is remove the relay and extend the two coil wires and two contact wires outside the casing and connect them to a more substantial standard 40 Amp relay and bond it to the case of the CEM ...

[keefer]

Thanks for the info and I now know I need the 30638708 version CEM to get my Volvo V40 D S through the MOT next month. I currently have the wrong CEM fitted and have lights and wiper issues.

Anyone got one that you might consider selling to me please?

Many thanks

Keith

[gatos]

Thanks for the info and I now know I need the 30638708 version CEM to get my Volvo V40 D S through the MOT next month. I currently have the wrong CEM fitted and have lights and wiper issues.

Anyone got one that you might consider selling to me please?

Many thanks

Keith

I do have a spare one and I can program it for rear wiper and fogs.

What is your problem/symptoms exactly?

[keefer]

Thanks for the quick reply! :)

From memory and without a full check, my problems are:

No indicators down both sides of the car.
No full beam unless I hold the stalk towards me (as if flashing your lights).
One of the rear wiper speeds doesn't work.

There may be other issues which I haven't picked up on and will do a full check over the weekend.

The original cem that came with the car is the 30621305 version which didn't give me dipped beam. The one from the scrappy now gives me dipped beam but not the aforementioned so it is definitely not the right one for my car.

It might be worth mentioned that the chassis number info you supplied suggest I should have the 30638708 version and is the one I'd really like to get hold of. Do you need any other details?

Many thanks :)

[gatos]

Thanks for the quick reply! :)

No indicators down both sides of the car.
You mean the indicators at the rear of the wing? Not sure if the CEM has anything to do with this. Have you checked the bulbs?


No full beam unless I hold the stalk towards me (as if flashing your lights).
Wrong CEM or wrong indicator would cause this. In your case wrong CEM


One of the rear wiper speeds doesn't work.
Never heard of this. Possibly CEM related, or dodgy wiper motor


It might be worth mentioned that the chassis number info you supplied suggest I should have the 30638708 version and is the one I'd really like to get hold of. Do you need any other details?
99% that I have one. Will let you know tonight

[keefer]

The indicators are the long thin ones, both front and rear and set in the ends of the bumper strips. Unless I imagined it and they're just reflective strips?

Thanks and look forward to hearing from you :)

[gatos]

The indicators are the long thin ones, both front and rear and set in the ends of the bumper strips. Unless I imagined it and they're just reflective strips?

Thanks and look forward to hearing from you :)


Aaaaa, ok. They are not indicators. We call them sidelights. Just check and replace the bulbs inside them

[keefer]

Lovely, thanks :)

[gatos]

Found it. I did a test on it in December and everything was working as it should and have also enable front fogs and rear wiper. Tried sending you a Private message, but apparently you have opted out of receiving or sending messages....:(. If you let me know your email, I will email you back and we can take it from there.

[keefer]

Great news :) Sending you a pm. I thought I've got everything enabled in my settings, if it's checked, it's enabled?

[keefer]

Can't send you a pm :( I get this:

Sorry, you can only send messages to the Administrators group until you have 30 posts.

[gatos]

My email is: gata958e @ googlemail.com

Without the spaces

[keefer]

Thanks for helping me out with my cem, you're a star :)

[caprirob]

Hi guys

Just posted a wanted ad but hope someone can help

When I bought my car I noticed that a single wire had been taken from one headlamp to another - obviously taking some sort of feed.

The headlamps worked and as it has been so cold I havent got round to looking at it.

Anyway a road trip last night saw both dipped beams fail and had to drive home with the mains on

A bit of digging suggests the CEM is at fault, however as the aforementioned bodge has been done it has been suggested in another thread that this will have damaged the CEM beyond repair.

The CEM on my car is 30859700

It is a poverty spec 2000 V40 with single headlamps and no foglamps.

Can anyone tell me will another p/n CEM fit - I believe the S40 ones will work but have to be programmed to make the rear wiper work - is this hard to do ? mine does not seem to have a variable rear wipe - it swipes with the wash button or on the switch.

There are none currently on ebay matching my P/N - any help gratefully received - can't pm back yet as not enough posts so please post on this thread or my wanted thread

[caprirob]

These are the various part numbers for the CEM:

Control unit [-2001, L.H.D (30859699)] 30896697
Electronics box [2002-, L.H.D (30621304)] 30638707
Control unit [-2001, R.H.D (30859700)] 30896698
Electronics box [CH 800000-026445, R.H.D] 30621305
Electronics box [CH 026446-, R.H.D] 30638708

By checking your chassis number (last 6 digits on your VIN) you should be able to find out which CEM your car should have.

What part number is the CEM you have?

The relevant relays are actually inside the CEM

So if mine has a 30859700 fitted now is the 30896698 a correct replacement ?

There is one currently on Ebay ( 30896698 ) but its described as being from an S40 so even if it will make the dipped beams work on my V40 the rear wiper wont ?

[caprirob]

This is getting right on my nerves

Managed to get 2 relays from Maplin yesterday unfortunately they are only rated 10A rather than 15A but a previous post on this thread indicated that should still be OK.

On removal of the CEM one of the relays was actually bulging so clearly something wrong with it.

Took me about 2 hours of fiddling to successfully de-solder and remove the old relays and then solder the new ones in.

Thought I had got a result when I plugged it all back in, ignition on, turned the lights on and went to the front of the car and saw them lit up

Unfortunately on turning off the switch and removal of the ignition key the headlamps stayed on !

So either the 10A relays arent up to the job and are permanently stuck on, or the CEM is knackered. Can anyone advise if the relays are too low amp-rated would this cause them to stick on regardless of whether the switch/ignition is on ? If so I can re-order the correct ones from RS - otherwise I Think I'm going to have to get to a breakers tomorrow and try and get a replacement.
I've been driving round all day with the headlamp circuit disconnected at the CEM - thankfully the brake lights and indicators seem to be controlled separately but I have no main beam with it unplugged and naturally can't drive it in the dark.

Does anyone within a sensible travelling distance of Cannock have a spare CEM I can try tomorrow ? 2000 Model V40 1.8 ( the date on the CEM I have is 10/99 )

[Clan]

This is getting right on my nerves

Managed to get 2 relays from Maplin yesterday unfortunately they are only rated 10A rather than 15A but a previous post on this thread indicated that should still be OK.

On removal of the CEM one of the relays was actually bulging so clearly something wrong with it.

Took me about 2 hours of fiddling to successfully de-solder and remove the old relays and then solder the new ones in.

Thought I had got a result when I plugged it all back in, ignition on, turned the lights on and went to the front of the car and saw them lit up

Unfortunately on turning off the switch and removal of the ignition key the headlamps stayed on !

So either the 10A relays arent up to the job and are permanently stuck on, or the CEM is knackered. Can anyone advise if the relays are too low amp-rated would this cause them to stick on regardless of whether the switch/ignition is on ? If so I can re-order the correct ones from RS - otherwise I Think I'm going to have to get to a breakers tomorrow and try and get a replacement.
I've been driving round all day with the headlamp circuit disconnected at the CEM - thankfully the brake lights and indicators seem to be controlled separately but I have no main beam with it unplugged and naturally can't drive it in the dark.

Does anyone within a sensible travelling distance of Cannock have a spare CEM I can try tomorrow ? 2000 Model V40 1.8 ( the date on the CEM I have is 10/99 )

what i would do is take the relay out , run 2 thin wires and two thick wires from the solder pads to the outside of teh casing and solder them to a conventional 40A relay and bond it to the CEM casing or fit it somewhere convenient , end of problem forever ...

[caprirob]

I spoke to an Auto Sparky mate and he reckons the Maplin relays are just wrong.
Have ordered the correct ones from RS as per earlier posts on this thread - should be here Wednesday.

Also had an ebay breaker contact me and offer me a box from a '99 1.6 V40 for £15 posted which I will take as well just in case.

I will have to get round the problem until then by driving round with the lighting circuit unplugged, and the under-dash panel removed so I can just plug the lights in if I need to drive in the dark.

[caprirob]

Properly annoyed now - Relays arrived from RS - desoldered the Maplin relays and re-soldered the RS ones in place

Still no good - as soon as you plug the lights loom into the CEM the dipped beams come on whether the switch is on or the key is in the ignition

I've gone from having no dipped beams at all to dipped beams that wont switch off unless you disconnect the CEM

Looks like the CEM has had it - so :

Are CEM's interchangeable or do i HAVE to get the correct matching p/n ?

If I get one from a higher spec car ( with fogs or twin lights for example ) as mine is basic spec with single lights and no fogs will this matter ?

And does anyone have one that they know works from a V40 not an S40 so I dont have to mess around getting it reporgrammed ?

[gatos]

I think I have one 30896698left, that I can program to whatever you want

[caprirob]

Thanks Gatos - just done a buy it now on ebay for one with that same p/n that the seller says is 100% and has been taken from a V40 so fingers crossed - if it doesnt work I'll be back to you

[caprirob]

I can now 100% Confirm that if you buy the relays, solder them in and it puts your lights on permanently with no keys in ignition or light switch on your CEM has had it.

I can also confirm that a 30859700 can be replaced by a 30896698 as long as its confirmed from a V40 ( if you have a V40 and need rear wiper etc ) and it WILL work

I now have working/controllable lights again

[Clan]

30859700 is superseded to 30896698 and is listed for a S40 RHD 2000-2001 model year . I have one going spare , but unfortunately do not know the condition of it as i cant test it .
send a PM if it is needed ..

[caprirob]

Thanks Clan but already done the trick through Ebay - the seller told me he tested it on a V40 first and the rear wiper works so its all good again now.

[Clan]

thats great news for you , lets hope it outlasts the car now :-)

[caprirob]

thats great news for you , lets hope it outlasts the car now :-)

I think the reason the original CEM was shot was due to a bodge by the previous owner - one relay failed and rather than do the relay replacement detailed in this thread he simply took a feed from the headlamp on the working side across to the non working side - so one relay was running both lamps.

I read on another forum than this will overload the CEM - and it was right.

I will try and retrieve the RS relays I fittted to my old CEM but I wasnt able to remove the originals without breaking them - my soldering skills arent that great :-(

Really pleased to have a fully working car again now though

[big buddha]

can anyone tell me which relay controls the front wipers on a 2001 v40? having issues with it, might change relay if I can find out which one it is, thanks

[shanegtr]

can anyone tell me which relay controls the front wipers on a 2001 v40? having issues with it, might change relay if I can find out which one it is, thanks
Im working on the same issue myself, but I also have the rear tailgate wiper not working as well.

Many thanks to the OP for the info, its been a great help so far - just another piece in the puzzle

[shanegtr]

Just pulled my CEM apart last night. Voltage going in for both the front int and rear wipers, but no voltage coming out after the relay's. So Im fairly confident that I've got burnt out contacts in the relays. Once I source some replacements I'll have a crack at a removal and replace.

[olliewilson87]

Hi all,

Having headlight issues with my recently purchased 1997 s40. Guessing from forums that the cem is to blame. I have checked and double checked under the dash in drivers footwell but it's not there!

Does a 1997 (r reg, may be a 98) have a cem? If so where is it? If not what is causing the problems?

Drls work
1 dipped beam works (very dull, duller than drl)
Main beam won't stay on (could click be broken on stick)

Response very very appreciated.

Thank you.

Ollie

[gatos]

Your car does not have a CEM. It was introduced at some point in 1999

[olliewilson87]

Thanks Gatos, i'm not going mad at least!

Any ideas where I should start investigating? Still likely a relay issue?

Thanks

[Mgualber]

Thank you so much for the information Unfortunately I can not open the pdf. provided. Can you please let me know if you still have them available.

[v40Carl]

Hello All, im new to the forum and need some advice on my v40.
I used to have an s40 and a classic 340 but never came across any prolems like it!

I got the car last week and this problem has been really annoying!

The 'low beam' does not seem to work, the running lights are always on when the ignition is on. I tried disconnecting the switch and the running lights remain on. when the switch is connected and moved to 'low beam position' i can hear the relays in the CEM clicking. full beam works fine.

After playing with this i checked the lights and wiring, the bulbs look new, there was a wire cut in the headlights and joined to the other side with a wire, i removed the wire and re joined the original wire back up and it's still the same... I guess that someones already been messing with it, the CEM looked like it had come from a scrapper at some point because it's got tip ex on it saying what car that it came off originally.

Am i wasting my time trying to fault find it? should i try a new CEM? don't really want to buy one if it's not going to fix it, and as you know main beam is important so i do want to get it fixed!

Also i'm having the same problem as the previous poster, i can't seem to get the wiring diagram on the first post to load?

Thanks in advance! :)

[woollymw]

[CEM Headlight Module]=Woollymw_S;470421] Hi, I have a similar problem with my twin headlights on V40 2.0T. Offside front headlight failed. I have exchanged the CEM with a replacement but this does function as it should. The Main lights work fine but when I switch to main beam the Dipped lights go out, ie I either have the two outer lights working or the two inner, but not all four together as they should be. Doeas anyone know if this is a programming issue as the the two CEM units have the same coding and internally look identical. I have also tried opening the pdf attachments for the Headlight Wiring and Pin identification but these do not appear to be working (have these now been removed from the forum site ?) If anybody can supply these to me that would be great.


Regards

Mark[/QUOTE]

[woollymw]

Hi, I have a similar problem with my twin headlights on V40 2.0T. Offside front headlight failed. I have exchanged the CEM with a replacement but this does function as it should. The Main lights work fine but when I switch to main beam the Dipped lights go out, ie I either have the two outer lights working or the two inner, but not all four together as they should be. Doeas anyone know if this is a programming issue as the the two CEM units have the same coding and internally look identical. I have also tried opening the pdf attachments for the Headlight Wiring and Pin identification but these do not appear to be working (have these now been removed from the forum site ?) If anybody can supply these to me that would be great.

Mark

[imoLV]

Maybe post author can reattach attachments ?
Volvo CEM Headlight Wiring.pdf and Relay datasheet.pdf seems it is gone ... :(

[runwld2]

YES, please, I really need the CEM diagram, and could also use a whole car wiring diagram if some one knows where it can be found.

[JBanks]

how much?

[gatos]

how much?

How much what?

[RMBBob]

Hi, I've recently had a headlight problem which, at first, appeared to be the common CEM issue (see this thread http://www.volvoforums.org.uk/showthread.php?t=67437) but finally turned out to be a break in the wiring loom. However, while fault finding the problem I found out a bit about the CEM which I thought others could find useful in faulfinding their own headlight related issues. I've taken a few pictures to help with this.

I have attached to this thread the Volvo wiring diagram for the CEM and headlights because the Haynes manual is worse than useless in this respect as it doesn't even show the CEM in their wiring diagrams.
I have also attached the data sheet for the Fujitsu relays that are used for the headlight switching in the CEM. I originally assumed that they would be solid state relays but in fact they are normal miniature PCB mounting mechanical relays so it they do fail then the data sheet could help find a replacement to repair the CEM.

Firstly, for those who don't know where the Central Electronics Module (CEM) is situated, here is a picture:
http://i93.photobucket.com/albums/l74/RussellS_2006/CEMLocation.jpg


Next we have a picture of the CEM circuit board itself highlighting the headlight relays:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMPCBRelays.jpg


and now a picture of the CEM connectors and their pin numbering to go with the attached wiring diagram:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMConnectors.jpg


Hopefully others will find this information useful as the CEM does appear to be a weak component with respect to headlight switching.


Regards

Russell


Many thanks for all that info Russell.
I am having a problem opening the two PDF attachments. Are they still functionable after 4 years?
Tried different browsers, and all security settings.
I just get a PHP (GIF Image, 1 * 1 pixel).
Can anyone help me on this wee prob?

[Thethompa]

Hello.
I had this problem with my right low beam not working. After reading this Most helpfull thread i removed and opened the CEM on my V40-03 2,0T.
I located the relay for right low beam from earlier posts here, drilled VERY GENTLE a 3mm in the plastic cover over the relay, filled it with "oxide remover". Let the remover do its work for ½hour, put the CEM in to the car again...and Yes there was light! If/when the problem comes back i will buy a pair of new relay and change them.
Thanks again for a very helpfull thread!

[Mikes garage]

The rear wiper is R1 on left in CEM.

[vasys]

The rear wiper is R1 on left in CEM.

Hi, does anybody know what relay in CEM used for heating rear window and mirrors?

[sebaveh]

None. It uses external relay on yellow/creme board next to CEM.

[vasys]

None. It uses external relay on yellow/creme board next to CEM.

Thanks, problem fixed

[BREZ]

Has anyone got the two attachments that appear in the original post please as they no longer open or download.

Attached Files
File Type: pdf Volvo CEM Headlight Wiring.pdf (58.2 KB, 1487 views)
File Type: pdf Relay datasheet.pdf (67.1 KB, 1259 views)

[Shug]

Is it a headlight problem you have?

[BREZ]

Headlight problem plus other light problems too.
Have checked bulbs, fuses, wiring and voltages.
It does point back to the CEM on voltages.
Noticed those on ebay in Poland but rather wary of seller.

[Shug]

If you are capable of soldering, or know someone who can, best bet is to buy a couple of relays from RS components, easy to swap them out, sorts a dead dipped headlamp. I can get part number tomorrow if you want, cheaper than messing around with a new control module, which you don't know history of!

[BREZ]

The soldering is not a problem, neither is the relays.
The Panasonic JSM1125 are readily available and cost pennies.

However, as i stated above, "Headlight problem plus other light problems too." replacing one relay wont solve my issue.
The breakers yard owners here in Ireland admit Volvos are a rear sight in their possession. (Out of 8 i contacted/visited, all i found was a crashed S80 Automatic):thumbs_up:

[shaunv40]

What's your part number? Ask on here? Some one will have one for sale

[gatos]

If you are after a CEM, I have a spare 30621305 and a 30896698. Both are for the S40 with foglights enabled. When I get my DICE back, I will be able to program it for the V40 too enabling the rear wiper

[BREZ]

Hi gatos,
Thanks for your reply.
i cant send you PM (thought i had enough posts by now!)
What i need is the 30621305 one with the fogs but no rear wiper.
Price please with postage to Ireland if you can.
Plus method of payment.

BREZ.

[gatos]

I am after £30 for it plus £4.95 postage which is the cheapest for RoI. I have tested the CEM on my car and everything works as it should/ Let me know if you are interested and I will PM you my email. Paypal or BACS is fine by me

[BREZ]

Perfect gatos!
Paypal payment is perfect.
awaiting your email.
BREZ.

[shaunv40]

So if I have a CEM from a s40 it won't work in my v40 as the wiper won't work??

[gatos]

So if I have a CEM from a s40 it won't work in my v40 as the wiper won't work??


They are identical between the S40 and V40. Only difference is in the enabled/disabled functions. The S40 has the rear wiper function disabled, but it can be very easily changed with DICE....:)

[shaunv40]

When is your dice coming back?

[gatos]

When is your dice coming back?

They sent it yesterday, so you are looking at around 7-10 days. And I hope it works on my 1.9D.....

[shaunv40]

That's always the issue! My brothers one at his garage won't connect to my 1.9d tried all combos Laguna, Mitsubishi charisma, no joy though.

[gatos]

That's always the issue! My brothers one at his garage won't connect to my 1.9d tried all combos Laguna, Mitsubishi charisma, no joy though.

Same here. That is why I sent mine back, so they can add the missing chips, which hopefully will sort the 1.9D problem. Will keep you updated about it....:)

[youngmun]

Hi, I have just replaced the CEM on my S40 with one from a V40 (same part number) and I am getting 'key error, try again' message. Tried battery reset, no luck. How can I resolve this, do I need to get the key or the CEM reprogrammed? I am thinking of putting the old one back on again but wonder if there are any other ideas out there, before I do this. Thanks.

[gatos]

Hi, I have just replaced the CEM on my S40 with one from a V40 (same part number) and I am getting 'key error, try again' message. Tried battery reset, no luck. How can I resolve this, do I need to get the key or the CEM reprogrammed? I am thinking of putting the old one back on again but wonder if there are any other ideas out there, before I do this. Thanks.

As far as I am aware off, the CEM has nothing to do with the key. So not sure if there is a link or it was just a coincidence.
Can you provide a bit more info? Year of car, engine type and size?
What was the problem that made you change the CEM?
What was the part number of the old CEM and the replacement one?
Where exactly do you get the 'key error, try again' message?
Does the car start and drive?

[youngmun]

Hi Gatos,

Thanks for the response.

My car is an S40, 55 reg, 2.0 D. CEM part 30728906 which I had replaced with same part number CEM from a V50.

I have been getting problems with the doors failing to unlock, esp the front passenger door, inaccurate outside temperature (-40, or -----) and sometimes homecoming lights coming on without prompting. The problem seems worse when it rains! My indie advised few months ago when I had a major problem with doors not unlocking that it was likely the CEM and that they had also cleared a lot of fault codes which led them to strongly suspect it. They also did some work to prevent possible water ingress which they said may have affected it.

On replacing the CEM yesterday the car would not start at on turning the key, and it read 'key error, try again' in the display after a few minutes of inserting it.

Speaking to my indie and Volvo, they say the car has to have a software download to enable immobiliser and other security functions but will only work if the CEM is brand new, i.e. has not previously been programmed to a particular car's settings.

I have since put the old CEM back on the car and everything works fine like before (temperature reading -38 of course). I'm frustrated that it really looks like I have no other alternative but to buy a new CEM at eye watering prices to fix the problems above.

I also wonder if it might be the passenger door module rather than the CEM, given most other electrics work fine? When I give the side of the passenger door some firms knocks, sometimes this unlocks the doors!

[gatos]

I am afraid this section of the forum is for the earlier S40/V40 cars from 1996-2004. You will have more lack asking the same question in the right place http://www.volvoforums.org.uk/forumdisplay.php?f=58

The CEM function on your car involves a lot more parameters and has something to do with the keys/locking. See what people say in the right section of the forum and with a bit of luck a forum member with a Volvo DIE, local to you might be able to program it for free. See the map of users with DICE here: https://www.zeemaps.com/map?group=280351

http://www.volvoforums.org.uk/showthread.php?t=136759

Hope this helps

Also this is the list of things that can be programmed in the CEM for your car

http://www.volvoforums.org.uk/attachment.php?attachmentid=68116&stc=1&d=1385827012

[Clan]

Hi Gatos,

Thanks for the response.

My car is an S40, 55 reg, 2.0 D. CEM part 30728906 which I had replaced with same part number CEM from a V50.

I have been getting problems with the doors failing to unlock, esp the front passenger door, inaccurate outside temperature (-40, or -----) and sometimes homecoming lights coming on without prompting. The problem seems worse when it rains! My indie advised few months ago when I had a major problem with doors not unlocking that it was likely the CEM and that they had also cleared a lot of fault codes which led them to strongly suspect it. They also did some work to prevent possible water ingress which they said may have affected it.

On replacing the CEM yesterday the car would not start at on turning the key, and it read 'key error, try again' in the display after a few minutes of inserting it.

Speaking to my indie and Volvo, they say the car has to have a software download to enable immobiliser and other security functions but will only work if the CEM is brand new, i.e. has not previously been programmed to a particular car's settings.

I have since put the old CEM back on the car and everything works fine like before (temperature reading -38 of course). I'm frustrated that it really looks like I have no other alternative but to buy a new CEM at eye watering prices to fix the problems above.

I also wonder if it might be the passenger door module rather than the CEM, given most other electrics work fine? When I give the side of the passenger door some firms knocks, sometimes this unlocks the doors!

you are wasting lots of time and effort and money here , if you had taken it to a volvo dealer they would have told you it is MOST likely the door wiring connector , there was a recall for this and your car may be still covered for this . CEMs contain immobiliser details and are locked to the car they were built with If it is faulty it must be replaced with a new one ...

Was there any sign of wetness in the big green plug or CEM pins on the top right of the CEM ? That would be the wash pump pumping water up the loom ! unlikely but possible .. again a recall would have sorted this if the case .

[youngmun]

Thank you Gatos & Clan for the helpful information -esp.about what can be programmed for the CEM & advice about the door wiring connector, much appreciated. There was no sign of wetness, it was definitely dry.

My plan is to have another word with my local Volvo on Monday and see what they say alongside your suggestions. Hopefully I can get a speedy resolution if it's the door wiring connector- I did check it sometime last year and I am sure it was gold plated with no signs of corrosion but will see what Volvo say.

Thanks again.

[Clan]

Thank you Gatos & Clan for the helpful information -esp.about what can be programmed for the CEM & advice about the door wiring connector, much appreciated. There was no sign of wetness, it was definitely dry.

My plan is to have another word with my local Volvo on Monday and see what they say alongside your suggestions. Hopefully I can get a speedy resolution if it's the door wiring connector- I did check it sometime last year and I am sure it was gold plated with no signs of corrosion but will see what Volvo say.

Thanks again.

if it was gold then you would have already had the repair done . Just removing and refitting the plug should have a positive effect on the operation if it is playing up as it cleans the contacts .

[youngmun]

Hi,

Volvo confirmed yesterday that the recall work on the door wiring connector was indeed carried out. I will try your suggestion of removing & refitting it and see what happens.

Thanks!

[SteveV40]

I have just replaced the relay on my V40. Never done anything like it before, but it only took 45 minutes start to finish. Got the relay from RS in advance. I bought 3 for less than a tenner including postage. Many thanks to everyone who has posted on this as it has resolved a problem that has saved me having to find a replacement CEM. They all differ, and this was a much more straightforward solution than I imagined.
I thought I might add my notes for anyone wishing to try this.
The relay has 5 soldered points, and they are quite close together. Ideally you would heat all 5 at the same time to pull the relay free, but I only had a standard soldering iron. I started with the two end ones and heated them in turn one at a time, gently easing the relay a little at a time until the came free. I them went to the three at the other end, and followed a similar procedure, although it was less straightforward due to the close proximity of the 3 terminals. Gentle leverage with a small screwdriver underneath whilst heating each in turn eventually persuaded it clear. 4 of the 5 holes were partially obstructed by solder, so I wrapped some tape (for heat insulation) around a darning needle and then heated the solder wiggling the needle in as far as possible, and then wiggling it free as the solder cooled. repeating several times on each hole until they were clear. Then mated up the new relay, added some new solder to the terminals, being careful nor to spread it around, and back into the car. Absolutely thrilled when the headlamp came on.
Thanks to all, and hope this helps encourage someone else to try this. Best wishes.

[Matt86]

I have just replaced the relay on my V40. Never done anything like it before, but it only took 45 minutes start to finish. Got the relay from RS in advance. I bought 3 for less than a tenner including postage. Many thanks to everyone who has posted on this as it has resolved a problem that has saved me having to find a replacement CEM. They all differ, and this was a much more straightforward solution than I imagined.
I thought I might add my notes for anyone wishing to try this.
The relay has 5 soldered points, and they are quite close together. Ideally you would heat all 5 at the same time to pull the relay free, but I only had a standard soldering iron. I started with the two end ones and heated them in turn one at a time, gently easing the relay a little at a time until the came free. I them went to the three at the other end, and followed a similar procedure, although it was less straightforward due to the close proximity of the 3 terminals. Gentle leverage with a small screwdriver underneath whilst heating each in turn eventually persuaded it clear. 4 of the 5 holes were partially obstructed by solder, so I wrapped some tape (for heat insulation) around a darning needle and then heated the solder wiggling the needle in as far as possible, and then wiggling it free as the solder cooled. repeating several times on each hole until they were clear. Then mated up the new relay, added some new solder to the terminals, being careful nor to spread it around, and back into the car. Absolutely thrilled when the headlamp came on.
Thanks to all, and hope this helps encourage someone else to try this. Best wishes.

A de-soldering pump tool makes this job easier as well.

[Clan]

If i had to do this i would run the wires from the solder pad outside the CEM and connect to a good old 40A relay . no more troubles then :-)

[Rossc0]

Morning guys.

I've been having headlight issues too.

My passenger side main beam isn't working. I've replaced bulb, checked fuse etc etc. I got a used CEM from a scrap yard and changed it over, still not working.

Do i just need to plug the new CEM in, or do i need to disconnect battery etc? Next job is volt meter test i think

[baldmosher]

that's the first job ;)

to quote someone else, if there's 0V across the bulb with the bulb in, and 12V across the contacts with the bulb out, then it's a faulty relay, otherwise it's the wiring

[sagardner]

Hello
Sorry if I have not checked all the info previously in the thread, but I have found it incredibly useful and managed to acquire a 2nd hand CEM for my V40 (2002) to fix a dipped headlight problem, but as a result(assumption), the rear wiper does not function.
My handbook does not refer to any fuses for this, but one thing I did do was to take a fuse out of No. 30 in the engine compartment fuse box to put into th dipped headlight as I had lost it. My handbook refers to 32 as a reserve, but there wasn't one, 31 which had non as 'VAC pump' and 30 as 'Charger AC (...options)'.
Can anyone advise if any of the above will have impacted the rear wiper, whether I need a fuse in No 30, whether the rear wiper may have been an error in the 'new' CEM I fitted etc.
Hope it all makes sense.
PS. I am not good with cars but this forum has probably saved me £500+ in main dealer charges already so much appreciated.

[gatos]

The rear wiper function needs to be programmed in the CEM. If the CEM came from an S40, the rear wiper function will be disabled. It can be easily be programmed with a Volvo DICE. See if there is a memnber near you who can do it for you FOC

[v40alex]

Hi, sounds like you have used a CEM from an S40, it is the same part number but the rear wiper is disabled. There is a fuse (#14) and a relay in the CEM, but if it was an S40 CEM, all you need to do is find someone with DiCE (good indie, main dealer or someone on the forum) then they can enable it for you.

Haha, didn't see gatos' message when I was previewing :)

[sagardner]

Thank you both
That does explain everything.
I am pretty ignorant about these things, but would have been good if the 'specialist' Volvo breaker had realised when he took the CEM out of the S40!!!
At least I now know what it is.
Many thanks for your help.

Is it possible that I could take the relevant bit out of the old CEM and replace it in the new one?

[gatos]

Thank you both
That does explain everything.
I am pretty ignorant about these things, but would have been good if the 'specialist' Volvo breaker had realised when he took the CEM out of the S40!!!
At least I now know what it is.
Many thanks for your help.

Is it possible that I could take the relevant bit out of the old CEM and replace it in the new one?

We all started by being ignorant and slowly slowly learned things. If you can't find anyone to do it for you, you can send it to me and I can program it for you. Just cover the postage both ways.

[baldmosher]

Gatos is there a thread somewhere listing the local owners with DICE? Or is it a case of being lucky, or turning up at one of the meets?

[gatos]

Gatos is there a thread somewhere listing the local owners with DICE? Or is it a case of being lucky, or turning up at one of the meets?


You can either pray to the Nordic gods for a DICE owner to pop up, or check here: https://www.zeemaps.com/map?group=280351 :D:D:D

[baldmosher]

That is cool. I am likely to try and set up a VM on my laptop as someone else has recommended it but I'll get in touch with RobbieH!

[gatos]

That is cool. I am likely to try and set up a VM on my laptop as someone else has recommended it but I'll get in touch with RobbieH!

I am using Oracle's VM Virtualbox to run Windows XP Pro on my Linux based laptop and it's perfect

[hart1mart]

Hi everyone was wondering if someone would be kind enough to help me out, I have a Volvo v40 D Sport 2002 model, I have read the entire posts concerning the CEM and think this could be the problem. I would like to have a go at trying a fix it. The problem is all lights were working fine until yesterday; I have lost side lights rear lights, licence plate light. All other lights front, hazards & main beam are all working fine. Can anyone tell me what relay controls the rear lights please, much appreciation to anyone who can point me the right direction. Many thanks in advance, Martin.

[baldmosher]

I don't know for sure, but that sounds more like a blown fuse... which in turn could imply a faulty wiring loom.... probably more likely if yours is a Phase 1 than a Phase 2 simply because of age. Have you checked the two fuse boxes first (I've no idea which fuses it'll be but no doubt there will be threads on here)? Replacing that might get you going at least although no telling if it'll pop again next time it rains.

If there is a CEM relay that controls all those lamps, then be warned that the solder is coated with some kind of anti-melt coating which means you'll have a right job removing the old solder. It's doable but it's a right faff, or so The Wife™ tells me, she does all the soldering around these parts.

[gerowr]

Hi, I've recently had a headlight problem which, at first, appeared to be the common CEM issue (see this thread http://www.volvoforums.org.uk/showthread.php?t=67437) but finally turned out to be a break in the wiring loom. However, while fault finding the problem I found out a bit about the CEM which I thought others could find useful in faulfinding their own headlight related issues. I've taken a few pictures to help with this.

I have attached to this thread the Volvo wiring diagram for the CEM and headlights because the Haynes manual is worse than useless in this respect as it doesn't even show the CEM in their wiring diagrams.
I have also attached the data sheet for the Fujitsu relays that are used for the headlight switching in the CEM. I originally assumed that they would be solid state relays but in fact they are normal miniature PCB mounting mechanical relays so it they do fail then the data sheet could help find a replacement to repair the CEM.

Firstly, for those who don't know where the Central Electronics Module (CEM) is situated, here is a picture:
http://i93.photobucket.com/albums/l74/RussellS_2006/CEMLocation.jpg


Next we have a picture of the CEM circuit board itself highlighting the headlight relays:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMPCBRelays.jpg


and now a picture of the CEM connectors and their pin numbering to go with the attached wiring diagram:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMConnectors.jpg


Hopefully others will find this information useful as the CEM does appear to be a weak component with respect to headlight switching.


Regards

Russell
I have just joined the Volvo forum and found information for use on my 2003 S40 with headlight problems. I found good info, but I cannot open the attached pdf files for some reason. The file opens showing only the link info and never opens or downloads the pdf file. What am I doing wrong? What I reall y need is the wiring diagram from the CEM module to right and left low beam lights. Thanks.

[v40alex]

You're not doing anything wrong, the forum moved to a new server but unfortunately attachments couldn't come for the ride.

2003
http://www.volvowiringdiagrams.com/volvo/S40%20V40%20V50%20Wiring%20Diagrams/TP3965202%20S40%20V40%202003%20Wiring%20Diagrams.p df

[Rossc0]

So I've done some investigating into my problem. I bought another CEM from the local scrapyard for £5, plugged it in but no joy. Started prodding with a power probe, probing the wire for the blown headlight, as it comes from the CEM makes the light illuminate. So surely can't be broken wires. I'm assuming I've got another dud CEM. Anyone got a CEM ending in 305 for sale ASAP?

[Rossc0]

Bought a working CEM, still no luck.
Any ideas? I'm stumped

[v40alex]

Did you do your voltmeter tests? I'd check the wiring that goes under the radiator - it's a known point of corrosion.

[Rossc0]

Did you do your voltmeter tests? I'd check the wiring that goes under the radiator - it's a known point of corrosion.

But if that was knackered then me putting power through the wire that comes out from the CEM (putting power probe into the wire right behind the plug for CEM) surely wouldnt light up the headlight bulb like it did.
Also my full beam has now gone too

[baldmosher]

It's not the wiring going INTO the CEM shorting out is it? Maybe try a new stalk or headlight switch unit perhaps?

I've got a left hand stalk spare if you want to try it, £10 posted, if it doesn't solve the issue then just keep it as a spare or put it on eBay. NB: I can't actually remember if it's the left or right stalk that flashes the headlights :D

[Rossc0]

It's not the wiring going INTO the CEM shorting out is it? Maybe try a new stalk or headlight switch unit perhaps?

I've got a left hand stalk spare if you want to try it, £10 posted, if it doesn't solve the issue then just keep it as a spare or put it on eBay. NB: I can't actually remember if it's the left or right stalk that flashes the headlights :D

Thanks but I've tested them and they both seem fine

[v40alex]

If you've run power and the lights light up, then that would seem to suggest the wiring is ok south of the CEM. Is your replacement replacement CEM ;) definitely ok? You really need another car to drop it into to be sure I suppose. I'd double check the continuity all the way through - the bulbs might still light if there is a bad earth somewhere.

And what happens if you test the voltage at the bulb holder - test it across the holder with the lights on, with bulb in the holder and without and see if there is a difference in voltage.

Also what year is your car?

[baldmosher]

And what happens if you test the voltage at the bulb holder - test it across the holder with the lights on, with bulb in the holder and without and see if there is a difference in voltage.

This is how I diagnosed the faulty relay. Still have two going spare at cost price + P&P if needed.

[Rossc0]

I've used 3 different CEM modules, all have been tested and work

[Rossc0]

also its a 2003 1.9d sport v40

[baldmosher]

I've used 3 different CEM modules, all have been tested and work
Confused now. If the CEMs don't work in situ, and you're getting light from the bulb by shorting in a live after the CEM, then how have you tested and confirmed that the CEMs work?

[v40alex]

Not sure if you already have this, here's the pinouts for the CEM

[Rossc0]

Confused now. If the CEMs don't work in situ, and you're getting light from the bulb by shorting in a live after the CEM, then how have you tested and confirmed that the CEMs work?

Plugged them in to another V40

[v40alex]

What was the result of the bulb holder bulb in/out test?

[baldmosher]

Are any of the contacts corroded or just dirty? "Lit" is not the same as "fully lit", so could be a bad connection somewhere, or maybe the wrong resistance is fooling the CEM somehow. Most multimeters will measure the resistance across a circuit, if one bulb lights and one doesn't, then you have a fair test for comparison of the Ohms.

Are you definitely absolutely sure it's not the switches failing?

This sounds like a right pita

[Gladston]

Hi,
I am having a prblem opening the PDF's. I am a member but I am still struggling. Is it an issue or just my PC :)

Thanks

[amillar]

The attachment in Matt86's post here http://www.volvoforums.org.uk/showthread.php?t=67437 works fine for me - most of the others seem to have disappeared.

Many thanks to all on here for excellent postings - fixed O/S dipped headlight with £1.33's worth of relay from Farnell 910351 (although changed both N/S and O/S to be safe).

[Old Snail]

Hi, I've recently had a headlight problem which, at first, appeared to be the common CEM issue (see this thread http://www.volvoforums.org.uk/showthread.php?t=67437) but finally turned out to be a break in the wiring loom. However, while fault finding the problem I found out a bit about the CEM which I thought others could find useful in faulfinding their own headlight related issues. I've taken a few pictures to help with this.

I have attached to this thread the Volvo wiring diagram for the CEM and headlights because the Haynes manual is worse than useless in this respect as it doesn't even show the CEM in their wiring diagrams.
I have also attached the data sheet for the Fujitsu relays that are used for the headlight switching in the CEM. I originally assumed that they would be solid state relays but in fact they are normal miniature PCB mounting mechanical relays so it they do fail then the data sheet could help find a replacement to repair the CEM.

Firstly, for those who don't know where the Central Electronics Module (CEM) is situated, here is a picture:
http://i93.photobucket.com/albums/l74/RussellS_2006/CEMLocation.jpg


Next we have a picture of the CEM circuit board itself highlighting the headlight relays:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMPCBRelays.jpg


and now a picture of the CEM connectors and their pin numbering to go with the attached wiring diagram:
http://i93.photobucket.com/albums/l74/RussellS_2006/VolvoCEMConnectors.jpg


Hopefully others will find this information useful as the CEM does appear to be a weak component with respect to headlight switching.


Regards

Russell

Thank you for the information, I have just finished my repair and all is in working order. No issue in getting to the relay, (RHS) albeit I did find it somewhat difficult to remove the old one, ended up drilling out the pins. Had to break up old relay just to see what's inside, one small unit inside another! Anyway, thanks for your guidance, most helpfull.
Old Snail

[Cymro1986]

Anyone noticed that now the temperatures are dropping that CEM's are starting to play up again?

Mine played up the start of the year, has been fine all summer and now Drivers side light will sometimes go out.
Easy fix so far is a quick knock on the panel holding the CEM and on it comes again. :lol:

I have got a spare ready for when it goes from a V40 but dont think the other V40 had fog lights.

[druid]

You might be able to sent it to Gatos and he will reprogram it. Send him a PM!

[sco3ie]

Just like to say thanks to everyone for this thread. It keeps on giving! Replaced mine in my '02 S40, gaining kudos points from my mech friends. Got relays too late for my CEM, which I replaced with one from the breakers but I'll probably fix the original one and stick it on ebay to make some money back.

Well done, people :thumbs_up:

[shanegtr]

Big thanks to all who started this thread. I've just fixed my non working rear wiper (V40) and front intermittent wiper. Took me ages to finally order the relays, it was only when I re-read this thread I realised someone had posted the part on RS components. Good thing the australian site uses the same part number :) Anyway, I've updated the original photo with the relays I replaced

[Cymro1986]

Finally had enough of beating the living daylights out of my lower dashboard to get both my lights turn on and fitted my new CEM....what a difference.

Lights are now silly bright, drivers has been slowly becoming duller for the last month (the side with the dodgy relay), now both sides are same brightness and much brighter than before, plus I got lucky and the CEM I had was from a V40 with fogs so everything works.

:)

[ma70]

Great thread & doubtless will be useful when I get mine home at last, since I have the left dipped beam out (amongst others lol).

Seeing as how I'm such a cheapskate though I think what I'll be doing after checking the bulb, is giving the dash a friendly "tap" above the bonnet release & see if that makes a difference, then if it does I'll dremel the lid off the relay & clean the contacts with a points file! :D (my reasoning being, if they take 10years+ for the arcing to build up crap from new, if I clean even 80% of it off I'll have good relays for 8years+ & that should be more than enough for my needs :D

I'll post back how I get on, if this is the course of action I take. Hoping it's just a bulb but I doubt it somehow... Just fed up of waiting now, next week till I can get the car home & time's dragging worse than lily savage!

[v40alex]

As a fellow cheapskate, sorry, I meant green environmentalist, I like the sound of relay repair. Do let us know how you get on.