Rhs head light problem

[s40 man]

Can any one help me i have a problem with the headlamp put new bulb in nothing been having problems since I got the car with it going of and on as you drive it would go of then come back on again and stay on and so on but no it is of all the time now could this be a broken wire I check the wire harness with a check light at the plug and nothing might have to take it to a auto elec help any one uther lights fine

[coffeejunky]

Originally Posted by s40 man

Can any one help me i have a problem with the headlamp put new bulb in nothing been having problems since I got the car with it going of and on as you drive it would go of then come back on again and stay on and so on but no it is of all the time now could this be a broken wire I check the wire harness with a check light at the plug and nothing might have to take it to a auto elec help any one uther lights fine

Which year is it. If it is a Phase 2 (>2001) it will have a CEM, which has a known issue with faulty relays. Some later Phase 1 cars do have a CEM too, so worth checking. You need to check with a multimeter if you are getting 12v at the socket with and without the bulb installed.

[s40 man]

I'm not geting any power at the plug socket it is a 2003 and it has a Cem it is the h7 bulb that won't work do's the cem control these bulbs main beam and side light fine drivers side all works OK mabe a trip to the scrap yard then fo a cem

[s40 man]

I'm geting power for the side light and main beam but no power to the head light h7

[coffeejunky]

Originally Posted by s40 man

I'm geting power for the side light and main beam but no power to the head light h7

OK so as I understand it:
Sidelight W5Ws work.
Both Main High Beams work.
Dipped (single H7 DRL mode) does not work on the right side.

A failed CEM should give 12v to the socket without a bulb fitted. BUT, will cut to 0v with the bulb fitted. I haven;t experience this myself though and am only going by past knowledge posted in this section.

There is also the loom of death issue, which can cause issues with headlights too. The above tests is one of the only ones that should help you diagnose between the two.

If you do look to source a CEM be cautions as I believe they are different V40 to S40 (including different part #s) and some need the fog lights activated using VIDA.

EDIT: Also if you are getting 12v to the socket at all times, try cleaning the socket thoroughly with a solvent of some sort then coating the contacts in Vaseline and checking they grip the bulb firmly.

[s40 man]

OK 12v to the side lights and main beam but nothing to the h7 to me this must be a broken wire as I say it was working then going of then coming back on again now nothing the problem is finding the broken wirer

[s40 man]

Loom of death that doesn't sound good

[coffeejunky]

Originally Posted by s40 man

Loom of death that doesn't sound good

It is the loom running under the radiator. It is exposed to salty wetness and heat, a combination which results in damaged insulation, shorting and breakages. Easily fixed once you have it all apart and have visually inspected each wire.
Search google or these forums for 'V40 loom of death' or 'V40 radiator loom' for full info.

[s40 man]

So if there was a problem with the cem would I still get 12v at the socket and a broken wirer would have no 12v at the socket

[pierremcalpine]

Originally Posted by coffeejunky

A failed CEM should give 12v to the socket without a bulb fitted. BUT, will cut to 0v with the bulb fitted. I haven;t experience this myself though and am only going by past knowledge posted in this section.

I can confirm the above firsthand. I replaced the relay and all returned to normal. See guide below for details.