So when I bought the car, the lady told me that only the high beams worked becuase one night the lights went out and she did what she could do to get them back to work.

So Ive looked into and can't figure it out.

The light bulb works, I replaced the fuse from a fuse out of another benz. I looked at the connector and it was basically stripped and covered in electrical tape and one of the ground wires isn't covered with anything. I don't remember the fog lights ever working either.

Ive looked at the wiring schematic and could it be a frail wire, what would be the easiest way to fix this problem. I want to start driving my Mercedes but I can't afford a ticket just for not having the lights working.

Thanks,
Eugenio

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1980 240D Mercedes

If you know for sure the bulbs and fuses are good, it has to be either the switch or wiring. Look at the connector that goes to the light assembly in the engine bay. Pin 3 on each one should be your low beam power and pin 4 should be the high beam power. Use a voltmeter and check to see that you are getting power to each pin.

If that is good, re-connect the connector, and then unplug the headlights themselves and check for power there. If you do not have power there, the problem is bad somewhere between the headlight plug and the connector in the engine bay.

Good luck!

Glenn

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Answered your own question.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

look at the wires themselves. On my 83 the low beam power wire is colored yellow or yellow/black stripe. The high beam power is white or White/Black stripe. Ground wires are brown.

Hope that helps

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Post which fuse you replaced. There are four for the headlights: LH (9), RH (7), LL (13), RL (11).

The foglights tap power off the RL fuse. This is supposed to be a 16 A fuse, so it may be a problem with the fuse since your fogs are also out (maybe).

In order, I would:

Turn the low beams on, then pull the switch rearwards (this turns the fogs on in case you weren't aware). You won't get any orange/amber light in the switch. Walk around and check for lights. You should have all four.

If you have the fogs and left low, it's the low connector that's bad.

If you only have the left low, check the fuses. Turn off the fogs (push in) and the lows (rotate) and swap fuse 11 and 13. Check lows ONLY again. If the problem switched sides, you know it's the fuse. Find a 16 Amp fuse and put that back in there. Put the 8 A fuse back into 13.

If they don't work at all with a known good fuse, then you've probably got at least a connector problem for the lows and maybe a different problem for the fogs. Get a voltmeter (or even a basic continuity checker) and probe the right connector at pin 3. It should be a yellow or yellow/black wire. You're looking for +12 V there. If you have +12 V, then it's probably a bad ground. If you have a DMM, check for continuity between pin 2 (brown) and ground.

Take a pic of your connector and post that here.

http://www.youtube.com/watch?v=zLtGTAJouu4

here is a video

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1980 240D Mercedes

Against my better judgment I'll assume you're serious.

So the left headlight, when it's installed, does work?

Put away the chainsaw and pick up some proper electical tools like the lineman's pliers and a soldering iron.

You see on the back of the headlight assembly all the "pins"? And the plastic square on the ground? You've got to get those back in order.

From the rear the pins are

A B
C D

The holder needs to have those stubby sockets visible at about 30-40 seconds and again at the end reinstalled. The order is (again, from the REAR of the holder, like you were a socket going into the holder)

Grey/Green Brown
Yellow White

This means G/G = A (foglight); B = B (ground); Yellow = C (low), White = D (high).

That wiggly ground at 35 seconds is junk. Get a larger screw and snug that baby down tight to the fender wall. These connections MAY be enough to get the lights working but you really need to replace some of the wiring. I'd consider going as far back as the splices upstream of the headlight.

After that's ready we'll work on your turn signal.

And do everyone a favor and properly aim the headlights after they're back in. The factory sealed beams on these cars are weak enough, getting them aimed to point at the road properly is essential.

I found the frail wire but I was trying to follow it and it went up into the dashboard. Is there an easy way to replace this or do I need to take out the entire dash?

I already tried taking out the dash but it doesn't want to move much

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1980 240D Mercedes

What do you mean "frail"? Like "charred" because it was burned, like "corroded all to heck?"

Do you have a still camera, or a still mode? If so, use that. The video is too jumpy to help. Also, how about some colors for the wires.

One more try: It appears that in the video at 15 seconds there are approximately five or six wires. Which of those is "frail?"

What are the colors?

If there are six, this is what they go to:

Yellow: +12V for low beam when fuse is good and light is on.
White: +12 V for high beam, ditto
Grey/Green: +12V for fog when low beam fuse is good and fogs are on
Blk/Grn: +12V for right turn signal
Grey/Red: +12V for the running/parking lights
Brown: ground

yes its completely charred. Its the brown wire, I traced it all the way back as far as I could and it burnt off the coating on the wire, I checked it with voltmeter and it wasn't good

edit:
well actually though elimination it looks like its the black/green wire that's charred but when i look at the pieces that are left it looks like a brown wire to me

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1980 240D Mercedes

How many wires visible at the bunch shown at the 15 second mark and what colors?

Regarding the burned/corroded wire: if it's the Blk/Grn you can ignore that regarding the headlights. You'll need to fix it later for the turn signal.

Use your voltmeter, put a fuse in spot 11, turn your low beams on and check for +12 at the yellow line.

Do you have +12V?

Actually I have 7 wires and two of them are brown with one being charred

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1980 240D Mercedes

The only wires that dont have continuity now are the two brown wires, now should they have continuity? I don't understand why they should since they only ground and ground is available all around the car.

So my question is were do these brown wires lead?

And should these wires have continuity when tested with the ground on the battery?

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1980 240D Mercedes

If one of them is brown w/ a black stripe, it's probably the ground path to close the relay for the aux fan. I think the wires for the receiver drier also run in that bundle, so one of them may go there.

If you can get a solid chassis ground via a separate wire, then no, you don't need continuity through the brown wires in the harness. If they are "frail" and charred looking I wouldn't use them in any case since the insulation may be burned in the harness and you're asking for a short. That's a danger with the other wires as well, so I'd be attentive to burning smells.

You can go directly from your headlight ground pin to the chassis.

Assuming you get the lights back in using the colors listed above, I would make sure to test each light setting for a few minutes with the hood up and an assistant. When the lights - first low beam, then also high - have been on for a few minutes I would feel as much of the harness as possible for any hotspots or indications of a short or burned insulation. If the wires remain cool, you're probably okay.

I would limit the fuse to an 8A and skip the fog lights until you can be sure your harness is okay.

Reusing a damaged harness definitely increases the risk of an electrical fire. Be very very careful.