S40 V40: CEM Wiring/Repair Information

[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]

Originally Posted by 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:



Next we have a picture of the CEM circuit board itself highlighting the headlight relays:



and now a picture of the CEM connectors and their pin numbering to go with the attached wiring diagram:



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/Dk...rds=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]

Originally Posted by sebaveh

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]

Originally Posted by V40DS

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.

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.