S40 V40: CEM Wiring/Repair Information

[MidlandsV40]

Just an update to say that the relay was at fault, I purchased a spare box from one of the forum members which worked also I was told by the garage that when they re-fitted my original unit there was a clicking and after tapping the unit the lights came back on. Either way I'm happy as it only cost £40 plus I have a spare unit. One more thing , the unit that I bought was able to be plugged in without the need for programming, however since then the cruise control seems to work now and again, I'm unsure if this is a separate issue or related to the unit swap?

[agw9262]

Hi all

first post here, I found this really useful posting and forum while searching for an answer to a problem that just developed... I have a Volvo S40 2002 which has factory fit front fog lights. Serviced the car yesterday and while doing a number of checks i found that the side lights, front fogs and rear fogs no longer work - everything else still works as expected.

Consulting the Haynes (chocolate fire-guard) manual I figured it was probably a common control fuse or relay but then I found this thread.... and now guess it is the CEM.

It is pretty cold right now, -11 (I live in Sweden) so it could be a side effect of that but either way I want to get it fixed properly. I have read the thread end to end but couldn't find anyone who had this specific problem - most seemed to be dipped/full headlights. And the diagrams/pictures don't show which relay belongs to the fog lights and whether or not any part of that circuit is common to both sets and the side lights.

Can anyone offer any advice to help me please? I have no problem finding my way around a soldering iron and first plan this morning is to check for voltage at the lamp (per the instructions in the thread) for fogs and side lights and then locate/remove the CEM for a closer look.

Hope someone can help!
Thanks,
Andrew

[agw9262]

Thought I would post that I have managed to find & fix the problem which confusingly had nothing to do with the CEM itself but the fact that both side light bulbs had failed AND the accessory fuse in the engine compartment fusebox which feeds the switch, that in turn feed the sidelights, front and rear foglights. 2 new bulbs, 1 new fuse (odd that it had blown but could either be a fault that will come back or a spectacular bulb failure...) and we are back in business.

Thanks.

[druid]

never mind...........

[73Mark]

Hello

I would like to take a look at these pdf files but they don't seem to be here any more a blank page shows when you view them.

Would you be able to re-post them at all this would be a great help.

Thanks

Mark

[73Mark]

Hello

I would like to take a look at these pdf files but them don't seem to be working a blank page opens.

It would be a great help if you could re post them.

Thanks
Mark

[SMurphie]

Hi Folks
haven't been on the site for a while. I have a 2002 1.8i GDI Volvo V40. It seems that I now have a problem with my CEM unit as my dipped headlights are not working. Have checked out all the wiring, bulbs and fuses and all are fine. Just wondering if anyone would have a unit for sale. The car has front and back fog lights with cruise control.
regards
Stephen.

[Clan]

Originally Posted by SMurphie

Hi Folks
haven't been on the site for a while. I have a 2002 1.8i GDI Volvo V40. It seems that I now have a problem with my CEM unit as my dipped headlights are not working. Have checked out all the wiring, bulbs and fuses and all are fine. Just wondering if anyone would have a unit for sale. The car has front and back fog lights with cruise control.
regards
Stephen.

Back in the early 2000's there was a kind of recall to add resistive wire in series with the dip headlamps to make the bulbs last longer ( and in consequence reduce light output ! ) , this was crimped in where the dip beam wires come out of the CEM , these have given trouble over the years due to the heat developed in this resistance wire .. so cut the resistive wire our and solder the original wires back together.. It is not always the CEM relays at fault !

[gatos]

There is an easy test you can do to test if it is the relays in the CEM that are at fault. Remove the bulb and measure the voltage. If you are getting 12V, then it is 99.99% the case of a failed relay. If you get 0V, then it might still be the relays, but more likely it is a problem with either your headlight switch (not very common to fail), or most probably corroded main wiring under the radiator or driver's wing

[73Mark]

Originally Posted by Clan

Back in the early 2000's there was a kind of recall to add resistive wire in series with the dip headlamps to make the bulbs last longer ( and in consequence reduce light output ! ) , this was crimped in where the dip beam wires come out of the CEM , these have given trouble over the years due to the heat developed in this resistance wire .. so cut the resistive wire our and solder the original wires back together.. It is not always the CEM relays at fault !

Interesting I'm still trouble shooting my headlight fault everything keeps pointing back to the CEM. Maybe I need to look into this.

I've swapped the unit out with no joy. Volvo will be giving me a ring on Monday to see if there allowed to pass on the wiring diagrams for the headlight circuit. I'll also be asking if this free diagnostic check being offered can be run as well to see what light that throws on the problem.

Mark