Help, elec prob on road trip. - PeachParts Mercedes-Benz Forum

Sopicki · #1 09-20-2008, 11:52 PM

Hi all,

I'm on a road trip with my family right now and I've got a bit of an electrical glitch. Our car is a 1987 300e.

Symptoms are:

Dim passenger side headlamp (High beam selection causes lamp to extinguish completely)
Turn signals don't work (emergency flashers do though)
When turn signal is selected (either direction), outside air temperature display goes blank
Faint crackling sound from behind instrument cluster when turn signal is selected

I've got to make a 3 hour trek home tomorrow. I suspect a bad ground but I don't really have any resources with me.

Anyone have any suggestions?

Thanks in advance,

TOPGUN · #2 09-21-2008, 12:20 AM

With no resources, the easiest thing to check would be the battery connections. Good Luck.

mpolli · #3 09-21-2008, 01:45 AM

It will be pretty hard to get that fixed on the road, especially on a Sunday. You have to decide if it is safe to drive. I would make sure the wipers work and the brake lights work. Drive during daylight only. From what you said you should be able to make it home. Do you have those old type ceramic fuses? Could be a bad ground but could also be something on the positive side. Without the schematic it is hard to say what is common between the things you list. Maybe someone else will have a better answer.

Sopicki · #4 09-21-2008, 10:05 AM

Well,

I pulled the fuse for the turn signals and the right headlamp will come on bright. I put the fuse back in and the turn signals/temp indicator work fine now but the right headlamp will only come on dimly. Guess I'll leave the fuse in for the day drive and pull it out for the bright headlamp for any nighttime driving.

Anyone know what the 2 circuits have in common?

Thanks,

Sopicki · #5 09-21-2008, 09:23 PM

For what it's worth to someone who may search the archives for a similar problem, the defect was the plug on the back of the passenger side lightbulb. The ground plug had corroded and heated up to the point of failure.

Thanks to all,

dieselnutnj · #6 09-26-2008, 03:02 PM

check your grounds!

Sounds like your backfeeding through various circuits lookin for a ground. The ground wires are usually brown and go to bolts to various parts of the body. Should be a major one behind cluster, and a few out in engine compartment. Was it wet or rainy when the problem started?

mpolli · #7 09-26-2008, 03:14 PM

Quote:

Originally Posted by Sopicki

For what it's worth to someone who may search the archives for a similar problem, the defect was the plug on the back of the passenger side lightbulb. The ground plug had corroded and heated up to the point of failure.

Thanks to all,

The headlamp?

Sopicki · #8 09-28-2008, 09:00 AM

Sorry,

Yes, the passenger side headlamp socket. The bad ground was in the socket itself. It would appear that the socket may have come loose or the actual female part of the plug got stretched somehow, it's kind of hard to tell what caused the failure since the plug was melted. I will say that I had put dielectric grease in that particular socket on 12-15-06 when I replaced the lightbulb with a sylvania cool blue bulb so I don't think corrosion was the problem. Heat also wasn't the problem since just the ground side of the plug was melted.

When I purchased the car I removed all the ground bolts I could find, cleaned the contacts and replaced them after smearing on some dielectric grease. However, all the grounds looked very clean and good then (April '06)

The driver side headlamp socket had been replaced by a previous owner, but he had used a low temp socket and only crimped the wires. I soldered in 2 new headlamp sockets with high temp units I purchased at advance auto parts.

All is working fine now.

Thanks all for your suggestions and help!

mpolli · #9 09-28-2008, 03:30 PM

OK. But that doesn't explain all of your original symptoms such as turn signals, and temp display. Does it?

Sopicki · #10 09-30-2008, 08:59 AM

Mpolli,

I think that since there was no ground for the headlight, the current was back feeding other circuits and causing them to be erratic. Dieselnutnj suggested this might be a problem.

As soon as I fixed the ground everything worked fine, the reason I continued to add to this post was so if anyone else had a similar problem they would be able to connect the dots on what seem to be unrelated circuits.

Thanks