S40 V40: CEM Wiring/Repair Information

[Rossc0]

Originally Posted by baldmosher

It's not the wiring going INTO the CEM shorting out is it? Maybe try a new stalk or headlight switch unit perhaps?

I've got a left hand stalk spare if you want to try it, £10 posted, if it doesn't solve the issue then just keep it as a spare or put it on eBay. NB: I can't actually remember if it's the left or right stalk that flashes the headlights

Thanks but I've tested them and they both seem fine

[v40alex]

If you've run power and the lights light up, then that would seem to suggest the wiring is ok south of the CEM. Is your replacement replacement CEM definitely ok? You really need another car to drop it into to be sure I suppose. I'd double check the continuity all the way through - the bulbs might still light if there is a bad earth somewhere.

And what happens if you test the voltage at the bulb holder - test it across the holder with the lights on, with bulb in the holder and without and see if there is a difference in voltage.

Also what year is your car?

[baldmosher]

Originally Posted by v40alex

And what happens if you test the voltage at the bulb holder - test it across the holder with the lights on, with bulb in the holder and without and see if there is a difference in voltage.

This is how I diagnosed the faulty relay. Still have two going spare at cost price + P&P if needed.

[Rossc0]

I've used 3 different CEM modules, all have been tested and work

[Rossc0]

also its a 2003 1.9d sport v40

[baldmosher]

Originally Posted by Rossc0

I've used 3 different CEM modules, all have been tested and work

Confused now. If the CEMs don't work in situ, and you're getting light from the bulb by shorting in a live after the CEM, then how have you tested and confirmed that the CEMs work?

[v40alex]

Not sure if you already have this, here's the pinouts for the CEM

[Rossc0]

Originally Posted by baldmosher

Confused now. If the CEMs don't work in situ, and you're getting light from the bulb by shorting in a live after the CEM, then how have you tested and confirmed that the CEMs work?

Plugged them in to another V40

[v40alex]

What was the result of the bulb holder bulb in/out test?

[baldmosher]

Are any of the contacts corroded or just dirty? "Lit" is not the same as "fully lit", so could be a bad connection somewhere, or maybe the wrong resistance is fooling the CEM somehow. Most multimeters will measure the resistance across a circuit, if one bulb lights and one doesn't, then you have a fair test for comparison of the Ohms.

Are you definitely absolutely sure it's not the switches failing?

This sounds like a right pita