S40 V40: CEM Wiring/Repair Information

[ma70]

Originally Posted by 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.

Yes that's it, environmentalist! Going to collect the car shortly so I'll let you know what the score is later. I have a feeling the bulb will indeed be fine though! (I've cleaned normal 40a relays with success before by the way, they're easier to open as the lids only clip on though)

[bigboz]

Just had a similar problem, main beams wouldn't come on, traced back to a dead power supply into the cem, relay and cem were fine but no input = no output

[as298712]

Thanks to everyone for this amazing thread... I have a 2002 volvo s40 and the drivers side headlight has gone out...changed the bulb and no luck. I am thinking i will try to replace the relay but just wanted to make sure I am replacing the correct one. The picture posted on this thread shows LH dipped beam and RH dipped beam. Am I correct in assuming the LH dipped beam relay is for the drivers side headlight??

[DXMachina]

I would have assumed that LH is Left Hand and RH is Right Hand when facing forward

So if you're in windsor, UK, then no. If windsor, canada, probably yes

[v40alex]

Left and Right hand are always as if you are sitting in a seat and facing forwards.

[ma70]

Originally Posted by v40alex

Left and Right hand are always as if you are sitting in a seat and facing forwards.

What that man said By the way Alex, replaced my n/s bulb & sorted the burned plug and my headlights all work fine now so I shan't be delving into the CEM just yet. I would imagine it's fairly easy to clean the relay contacts in the manner I described though, just don't dremel through the field coil of the relay when you chop the lid off! (IIRC there was a photo of an opened relay somewhere in this thread so you can check that to see how deep you can go with the disc without hitting any innards)

[gatos]

Originally Posted by ma70

What that man said By the way Alex, replaced my n/s bulb & sorted the burned plug and my headlights all work fine now so I shan't be delving into the CEM just yet. I would imagine it's fairly easy to clean the relay contacts in the manner I described though, just don't dremel through the field coil of the relay when you chop the lid off! (IIRC there was a photo of an opened relay somewhere in this thread so you can check that to see how deep you can go with the disc without hitting any innards)

Problem is that there is a smaller relay within the relay..... And it is a damn small one too

[ma70]

Hmmm :/ I was aware it was a "Russian doll" relay, but unaware they were that small. The photo I saw of a dissected one looked eminently "reconditionable" but maybe the size of the photo distorted my perception
If I do ever have CEM trouble I'll still be trying it before replacing the relay (if I kill the relay no harm done, it was dead anyway)

[as298712]

Thanks for the fast reply. I just removed the old relay and soldered on a new one, and the headlight still wont work. I checked the fuses and they are fine. Is the only remaining culprit the wiring loom under the radiator? I don't know where to look from here.

[DXMachina]

At this point it is worth checking that the bulb works. It is not entirely unknown for a headlight to come out of the box faulty, just rare

Nor is it impossible that even the most competent car fixer might remove a bad bulb, put down the new bulb, and put the failed one back in

Then, a voltage test of the bulb plug contacts with headlights switched on, to see if any power at all is coming down the wires