Low Beam not working

[Fozzy Senior Member Find all posts View Profile Close Fozzy]

I've done a search on the forum under "low beam" and couldn't find anything that seemed to match my problem so here goes. Have a 2008 120 D4D.

Noticed that both LH and RH low beams aren't working. Parking lights are fine and so is high beam. Pulled the wiring connector off the RH headlight and plugged it into a spare lamp. Same result, no low beam, high beam OK.

Both fuses that ARE present are OK. Legend on the inside of the fusebox indicates that I should have 4 fuses, one each for LH and RH low and high beam, I only seem to have the 2 high beam fuses in place. Can't see any fuses on the little panel under the dash to indicate they have anything to do with the lights.

As an aside and it may be related to the issue, should I be able to switch the parkers/headlamps on/off with no key in place? I'm not certain but seem to remember that headlights would go out when the key was removed. At present I can switch on and off at will with no key in place.

Any clues would be much appreciated!

[MacroP Member Find all posts View Profile Close MacroP]

The headlights may turn off when you remove the key but you should always be able to override the auto off function by turning the switch off and back on again.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

All you can do is check for 12V on the wires starting at the lights themselves. It does sound like a relay or switch problem if both are out. Perhaps swap the high and low beam relays and see if you still have a problem. Otherwise I can see no alternative to tracing the wires and finding where the voltage goes walkabout.

[MacroP Member Find all posts View Profile Close MacroP]

As Chicken mentioned there's not much to discriminate your issue other than the stalk switch or the wiring to the headlight as you've mentioned that highbeam lights are working fine which eliminates the fuses, BCM, and the headlight relay as an issue.

Low beam is the red line below. Not much to go wrong here other than the stalk switch. Part diagram attached for purely educational purposes only.

[Corigator Avid PP Poster! Find all posts View Profile Close Corigator]

... and don't forget that the 08 D4D is negatively switched when you check for voltages.

[NaomiF Lurker Find all posts View Profile Close NaomiF]

Hey Fozzy, did you fina a solution? I'm guessing you did seeing as your post was years ago. I've got exactly the same problem, started yesterday.