1991 300D fog lights-inoperable? - PeachParts Mercedes-Benz Forum

dablk1 · #1 05-19-2011, 12:41 PM

After working flawlessly since I've owned the vehicle all 3 foglights have stopped working at the same time. I've checked the #4 fuse and it appears to be fine. Where or how should I start troublshooting this? All other electrical components work fine.

sjh · #2 05-19-2011, 12:58 PM

3 fog lights?

As best I recall my '90 300D only had the two on the front.

Do you nave third in the rear on only the driver-side?

Does that require one switch position to turn on the front ones and a different switch position to turn on the rears?

I'd take out my meter and see if voltage is present at the switch when I turn it to the on position for the lights as a starting point.

dablk1 · #3 05-19-2011, 01:07 PM

Yes I have 3. 2 in front and one on driver's side rear. 1 position for front and a second position for the rear.

sjh · #4 05-19-2011, 01:11 PM

Quote:

Originally Posted by dablk1

Yes I have 3. 2 in front and one on driver's side rear. 1 position for front and a second position for the rear.

My 210 was like that. I'll have to go look at my '90 124 and see if it's there and I've no noticed it.

It's pretty easy to take the plastic cover below the steering wheel off and measure if voltage comes out your terminals when the switch is turned.

Do you have the schematic for the lights. I think I do and can post it (eventually) if you don't.

However, it's probably best to wait and see if someone has already encountered that problem and can speak from experience.

dablk1 · #5 05-19-2011, 01:33 PM

I'll probably need the schematic as well as wait for others to chime in. Nevertheless I'll start by removing the plastc underneath the steering first. It's really weird, even the amber light that usually light up when the switch is in the second position, isn't even working.

compu_85 · #6 05-19-2011, 02:04 PM

I'd double check the fuse is good. Use a meter or test light.

-J

winmutt · #7 05-19-2011, 02:55 PM

And of course check voltage at light just to make sure its dead. Ground or switch is bad id think.

TheDon · #8 05-19-2011, 02:57 PM

Does the switch operate properly?

dablk1 · #9 05-19-2011, 03:21 PM

Well I'll double check and recheck the fuse again. I'm beginning to lean towards the switch. It functions as it always did.

Yak · #10 05-19-2011, 06:05 PM

Is one or the other headlights also out? Perhaps the right one?

Check that fuse, too. The fogs may be downstream of the headlight fuse.

dablk1 · #11 05-19-2011, 06:38 PM

The headlights are fine. As a matter of fact I just finished looking at the switch and without a schematic I have no idea with wires go where. I also rechecked the fuse again.

spark3542 · #12 05-19-2011, 06:39 PM

Turn off your highbeams.

dablk1 · #13 05-19-2011, 06:55 PM

Highbeams aren't on. I have Euros and I think that my fogs stay on even when highbeams are active although I never checked.

babymog · #14 05-19-2011, 07:10 PM

Fogs stay on with high-beams.

dablk1 · #15 05-22-2011, 03:23 PM

I'm still having no luck with the fog lights. I used a light tester and found that I had continuity at the fuse/holder/light with power off. When switched on it drops off. I'm leaning towards a bad ground. Unfortunately I'm not sure how to test the ground wires. Can anyone be specific about location/colors and testing procedures?