Left low beam headlight stops working on my 87 300D...Any Help? - PeachParts Mercedes-Benz Forum

davidlee · #1 05-08-2012, 02:40 PM

The problem Ive been having recently on my car is that sometimes the left low beam wont come on when I turn on the lights. at first I thought it was a fuse (#13) all looked well, I still did the proses of twisting all the fuses in their spots to possibly break up any corrosion that might have started. then I changed the fuse (#13) when that didn't work, I figured the bulb was the problem, so I changed it. still didnt work. so I shut my hood, started up the car to leave the auto parts store, turned my lights on and , Hey, what do you know they both worked. I kept my old bulb because I feel that was not the problem. I have also checked the harness connect at the lamp housing, looks fine, also the connects inside the housing look good. It does this to me about once a week now, I always go under the hood and check connects and fuses but find nothing.
when the left light starts working again, it doesnt just all of a sudden turn on by itself while the lights are on.
The lights have to be turned to the OFF position and then turned back ON then both lights might light up

xalu · #2 05-11-2012, 09:29 PM

I also am having this issue. Sometimes (more times then I would like) the left low beam won't come on.

I switched out the fuse (#13) and tested it with a meter. I changed the bulb. High beam works fine. But no low beam. I tested the voltage at the socket and there is no voltage. There looks to be a little corrosion where the low beam goes, but I scraped it off and jiggled, no change.

Have you found the solution?

Could be the actual switch inside the car?

JamesDean · #3 05-12-2012, 12:07 AM

I'm not sure about the 124 series cars but the 126 cars have his long relay in the fuse box.

Sometimes on my 420SEL a fog lamp wont come on. I tap the relay and the light turns on..

Alternatively, the problem might be in the turn-signal/combination switch. I've heard that they can effect the low-beams at times.

Jeremy5848 · #4 05-12-2012, 01:26 AM

All of the external lamps go through the lamp-out warning module. This is the longest relay in the fuse/relay box, on the left (driver) side of the 3 columns of relays in the box. I would check it last, after checking the lamps and their sockets, the fuses (replace the fuses with new ones just to be sure), the combination switch on the steering column, and the light switch itself.

Note that the headlamp circuits in your car use fuses 2, 8, 13, 14, 15, and 16. Check them all.

When you have the problem of the headlamp not working, do you get a lamp-out warning in your instrument cluster?

Jeremy

gastropodus · #5 05-12-2012, 01:51 AM

I have had problems with the darn aluminum (silvery-looking) fuses; they'll look just fine, but my headlights were intermittent. Problems went away when I put in higher quality fuses. They're not copper, but more of a brass type of material.

Kurt

Jeremy5848 · #6 05-12-2012, 11:19 AM

Agreed, the aluminum fuses oxidize with age and aluminum oxide is an insulator. Brass also oxidizes (corrodes) but is still a conductor. Switch all fuses to brass, please.

Jeremy

xalu · #7 05-12-2012, 12:50 PM

Okay, I'll try new fuses on everything. I am also going to cut the wire to the socket and test it.

My switch is in the dash, not the steering column just to be clear. I don't think it's the switch though because jiggling it around has no effect.

xalu · #8 05-12-2012, 03:10 PM

Replaced fuses, and cut the wire at the socket to test voltage. Still nothing.

How can I test the switches and relay?

Jeremy5848 · #9 05-12-2012, 04:27 PM

Sorry to use a big word.

The "combination switch" runs the turn signals and high-low-flash of the headlights. It is located in the steering column of all recent M-Bs including yours. The headlight wiring goes through that switch. It's unlikely to be the problem but you gotta check through the entire system, especially if the obvious stuff (fuses, sockets, bulbs, etc.) doesn't pan out.

BTW, I and others have had problems with bulbs that look and test good but the filament is actually disconnected on one side and is just touching the support. It works great until it doesn't and you never know when that will be. You might try swapping the bulbs left-right to see if the problem moves. OK, your first post says you changed the bulb. Scratch that idea.

If you haven't already, track down the ground (brown) wire for the headlamp and trace it to its terminal point on the body. Remove the screw and scrape/sand the terminal and body to bare metal. I had a lighting problem that was eventually traced to a bad ground. Again, not a good possibility since the high beam works but you never know.

Jeremy

xalu · #10 05-12-2012, 05:00 PM

Quote:

Originally Posted by Jeremy5848

Sorry to use a big word.

The "combination switch" runs the turn signals and high-low-flash of the headlights. It is located in the steering column of all recent M-Bs including yours. The headlight wiring goes through that switch. It's unlikely to be the problem but you gotta check through the entire system, especially if the obvious stuff (fuses, sockets, bulbs, etc.) doesn't pan out.

BTW, I and others have had problems with bulbs that look and test good but the filament is actually disconnected on one side and is just touching the support. It works great until it doesn't and you never know when that will be. You might try swapping the bulbs left-right to see if the problem moves. OK, your first post says you changed the bulb. Scratch that idea.

If you haven't already, track down the ground (brown) wire for the headlamp and trace it to its terminal point on the body. Remove the screw and scrape/sand the terminal and body to bare metal. I had a lighting problem that was eventually traced to a bad ground. Again, not a good possibility since the high beam works but you never know.

Jeremy

Thanks for the help. From what Ive been reading in the forum the combo switch works in pairs. So if it was malfunctioning I'd have bot low beams out. Is this correct? I looked at it and it looks like its in good shape.

The ground wire checks out. After all high beams are working.

Can I power the left low beam off the right or will they go dim?

Wish I could figure this out :/

davidlee · #11 05-12-2012, 05:59 PM

Quote:

Originally Posted by xalu

I also am having this issue. Sometimes (more times then I would like) the left low beam won't come on.

I switched out the fuse (#13) and tested it with a meter. I changed the bulb. High beam works fine. But no low beam. I tested the voltage at the socket and there is no voltage. There looks to be a little corrosion where the low beam goes, but I scraped it off and jiggled, no change.

Have you found the solution?

Could be the actual switch inside the car?

Hey xalu, I actually fixed the problem in my car, It was the Lamp Failure box located under the skrew off cover behind the fuse block.
Very common problem I found out with these cars,
It has a Hella logo on it, it's the only one that does. You can open it up and inspect it inside, I saw mine was disinegrated in the little aluminum maze's that run vertical. I touched the metal back together and everything works fine so far. Ill will be replacing it very soon, before You go pulling your steering wheel, and combo switch, check that out.

xalu · #12 05-12-2012, 07:14 PM

Quote:

Originally Posted by davidlee

Hey xalu, I actually fixed the problem in my car, It was the Lamp Failure box located under the skrew off cover behind the fuse block.
Very common problem I found out with these cars,
It has a Hella logo on it, it's the only one that does. You can open it up and inspect it inside, I saw mine was disinegrated in the little aluminum maze's that run vertical. I touched the metal back together and everything works fine so far. Ill will be replacing it very soon, before You go pulling your steering wheel, and combo switch, check that out.

Hey DavidLee,

Thanks for the tip..I have an 81 300d. I am not seeing anything other than fuses under the fuse cover. Must be your cars year. (unless you mean under under the fuses?)

The only relays I can find are not related to the lights. These are the two above left front tire, under plastic cover. I pulled them with the lights on and nothing happened.

davidlee · #13 05-12-2012, 11:23 PM

Nope you're right, I was talking about a 124.

edorazio · #14 05-13-2012, 07:35 PM

As these cars age, it is not uncommon for the headligh plug to short out. Result if that you lose low beam, generally.

Usually if you pull off the plug at the back of the headlight in question, you will see a "cauliflower" effect or arcing marks where the internals of the plug have failed.

Advance auto sells replace ment plug for a few $$$. Alternatively you can scavenge a junk yard for the headlight harness. Lastly, I believe that the Dealer can also accomodate with a new harness.

xalu · #15 05-13-2012, 07:51 PM

Quote:

Originally Posted by edorazio

As these cars age, it is not uncommon for the headligh plug to short out. Result if that you lose low beam, generally.

Usually if you pull off the plug at the back of the headlight in question, you will see a "cauliflower" effect or arcing marks where the internals of the plug have failed.

Advance auto sells replace ment plug for a few $$$. Alternatively you can scavenge a junk yard for the headlight harness. Lastly, I believe that the Dealer can also accomodate with a new harness.

Thanks, but as I explained above. I cut the wire and tested the current. It isn't the harness. The low beam wire never gets any voltage.