|
S40 / V40 '96-'04 General Forum for the Volvo S40 and V40 (Classic) Series from 1995-2004. |
Information |
|
CEM Wiring/Repair InformationViews : 218717 Replies : 357Users Viewing This Thread : |
|
Thread Tools | Display Modes |
|
Mar 1st, 2009, 13:41 | #1 |
New Member
Last Online: Feb 12th, 2011 11:22
Join Date: Apr 2007
Location: Waterlooville
|
CEM Wiring/Repair Information
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 |
Mar 1st, 2009, 18:46 | #2 |
Senior Member
Last Online: Oct 1st, 2019 08:50
Join Date: Jan 2009
Location: Preston
|
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!
|
Oct 6th, 2009, 20:18 | #4 |
Junior Member
Last Online: May 19th, 2010 23:14
Join Date: Feb 2006
Location: Milton Keynes
|
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
|
The Following User Says Thank You to spickee For This Useful Post: |
Oct 6th, 2009, 20:24 | #5 |
Idiot
Last Online: Apr 21st, 2019 17:29
Join Date: Nov 2006
Location: Derby
|
I wonder if this unit can be altered to turn off the DRL's :P
__________________
Vectra VXR estate convert Experience = V40 1998 2.0 CD lots of mods Busy pestering the poor sods here now |
The Following User Says Thank You to Dog_Book For This Useful Post: |
Oct 9th, 2009, 23:52 | #6 |
VOC Member
Last Online: Apr 1st, 2024 11:23
Join Date: Jul 2007
Location: Rosyth
|
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! |
The Following 2 Users Say Thank You to DeeJay For This Useful Post: |
Oct 12th, 2009, 14:42 | #7 |
New Member
Last Online: May 5th, 2010 11:49
Join Date: Sep 2009
Location: swindon
|
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).
|
The Following 3 Users Say Thank You to viavan For This Useful Post: |
Mar 10th, 2011, 22:31 | #8 |
Experienced Member
Last Online: Today 12:49
Join Date: Jun 2007
Location: L/H side
|
yes , just read your owner's handbook :-)
__________________
My comments are only based on my opinions and vast experience . |
Oct 14th, 2010, 13:03 | #10 |
Junior Member
Last Online: Jun 22nd, 2018 17:25
Join Date: Oct 2010
Location: Abingdon
|
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/s...7-2876&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. |
The Following 7 Users Say Thank You to qipan For This Useful Post: |
Currently Active Users Viewing This Thread: 2 (0 members and 2 guests) | |
|
|