S40 V40: CEM Wiring/Repair Information

[LPR]

Originally Posted by LPR

I have only parking lights, no dipped, no main beam.
I do herar click from cem with new relays for dipped lights, so I guess light switch is ok.
Also main beam blue light is gloving constantly if I turn light switch to daylight or lights on position. Main beam switch does do notihing.

Any ideas?

It was stupid burned ground connection. Blue light and non clicking main beam relay mislead me
Lesson: loose or lost grounding can make stange things.

[molemot]

Once again, this forum sorts it out....I'd lost the LH dip beam...bulb was OK...so I looked here! Instant diagnosis; ordered a new relay from Poland(!), then took out the module and had a happy time regressing to one of my old persona...electronics technician. Removed the relay and replaced it with new and all was well. A bit fiddly if you haven't done this stuff before, but what a cost effective fix!!! Many thanks to Russell S.....

[JaniP]

Same here!
Paid 5€ for parts repairing 600€ new part (CEM modul)!

Big Thanks to all smart and willing to help people on this forum!

[Andy256]

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

Hi although I'm a member of this site I still can't see those photos, can you please repost them , thanks Andy

[S40wolf]

Hi does anyone know where the boot light on S40 2003 get it's power from as I want to run separate wire because the boot lid wireing loom is plàying up when moved so think I might have a broken wire inside

[gatos]

Wiring diagram here: http://www.matthewsvolvosite.com/dow...03_S40_V40.pdf

[aldred309uk]

Does anyone know where I could source 2 dipped beam relays from? I've tried searching the code on the relay on eBay to no avail and wouldn't know where to start when trying to find one elsewhere.

P1CN012W1

Many thanks, Adrian.

[Clan]

Originally Posted by aldred309uk

Does anyone know where I could source 2 dipped beam relays from? I've tried searching the code on the relay on eBay to no avail and wouldn't know where to start when trying to find one elsewhere.

P1CN012W1

Many thanks, Adrian.

Radiospares/Farnell will have one if you have a pattern , They should be easy to obtain elsewhere too .

[aldred309uk]

Originally Posted by Clan

Radiospares/Farnell will have one if you have a pattern , They should be easy to obtain elsewhere too .

There's a place called CPC Farnell near me in Preston which I was considering trying as second in my list tomorrow, an auto electrician is willing to do the replacement for me should I source the part.

That's for the tip!

[aldred309uk]

To anyone looking for relays to replace your old ones, the original relay (P1CN012W1) has been discontinued and is tricky to find. I purchased my relays from RS components for £2 each. The relays I bought are made by Panasonic and it comes up as (JSM1-12V-5) and they have worked on my car.