2001 C320 Tail light issue - PeachParts Mercedes-Benz Forum

FastEddy · #1 10-11-2004, 01:30 AM

I have a 2001 C320 Sport purchased in late 2000 with 24,000 miles.

In the last 2 months I have had to have the dealer replace 5 tail lamps on the drivers side. All different lamps. After the 2nd one went out I had them replace all the lamps with new ones. They still kept blowing. When the 4th one went, with much resistance from the dealer I had them replace the circuit board that the lamps mount to. They said there was a small amount of corrosion in the sockets. 4 days later a lamp blew on the passengers side.

At this point the car is 3 days out of warranty. I immediately took it back to the dealer. They have had it for 5 days now and I when asked whats up, they tell me they are testing and cant find anything wrong. They also say they are trying to get Mercedes to cover any work under warranty.

1- Has any one heard of this being an issue with others?
2- What could be causing this?

Something doesn't seem right to me.
I will be talking to them at some point this week and would like to know a bit more about what they may or may not be telling me. Could there be a major issue that the dealer doesn't want to bear the warranty expense on?

Past warranty work on the car has been, electrical failure of the center console and replacement of a window motor.

TROVERMAN · #2 10-11-2004, 10:55 AM

My 95 E320 wagon blows taillamps one right after another. I have heard 2 reasons: 1.) European cars have had exterior lighting issues for years and will continue to have them (My neighbor has an '01 Volvo S80 with major outside lighting issues too)
2.) On MB's the cruise control is somehow wired into the brake lights and this can blow bulbs.

Your car is new enough to probably have some sort of message center in the dash that tells you when a bulb is out? We have a 96 Explorer LTD with this feature, and one headlight wouldn't operate. It turned out to be the bulb monitor which tells you if the light is working or not. This could be the case with your car.

Richard Wooldridge · #3 10-11-2004, 12:00 PM

Hi there,
As far as I know, there are only a couple reasons lamps fail. One is high voltage, the other is vibration. If your alternator's voltage regulator isn't doing it's job correctly, the voltage could be getting too high and causing the taillights to go, but I'd think the headlights would fail first. If there is excessive vibration at the rear of the car it could cause the filaments in the lamps to fail due to metal fatigue, but your Merc shouldn't have that problem!
Maybe the real problem is that they have reached the end of their life cycle, and are just going out one at a time. I would check the voltage first - if it's getting above 15.5 volts you have a problem.
Good luck with it!

Regards,
Richard Wooldridge
'82 300D/4.3L V6

Ethan · #4 10-11-2004, 01:55 PM

Ask them to put in writing why there would be any issue of warranty.

I think by federal law - this is not a state issue - they cannot charge you for an ongoing repair issue even if the car goes out of warranty while the issue is being handled.

www.nhtsa.gov go there and ask them and if you have any problems file a complaint.

manny · #5 10-11-2004, 02:58 PM

Quote:

Originally Posted by TROVERMAN

2.) On MB's the cruise control is somehow wired into the brake lights and this can blow bulbs.

Last time I looked, ALL cruise controls are wired into the brake switch circuit.
That's how it gets " kicked " off.
Safetyfeature.........would'nt want to step on the brakes, & have the cruise trying to maintain speed.

TROVERMAN · #6 10-13-2004, 10:52 AM

Brake switch activates brake lights--cruise is on the same circuit, at least on some MB models--the MB CC unit is sensitive so that if a brake light is out more amperage goes to the cruise circuit than usual, possibly causing damage and then messing other things up.

Richard Wooldridge · #7 10-13-2004, 11:49 AM

Hi Troverman,
I don't know who filled your head with that nonsense about the cruise control "drawing more current if the bulb is out", but it is complete nonsense. The cruise control senses the voltage level at the bulb though a high impedance sensing circuit that cannot draw any significant current at all. If the bulb is out, it draws even less current than normal. (in the range of microamps, not even milliamps!) Manny correctly informed you that the cruise control is connected to the brake lamp circuit on almost ALL cars, not just Mercedes cars! (Some GM vehicles used a separate switch on the brake pedal for a few years) The Mercedes cruise control amplifier has been problematic, but not because of brake light bulbs, instead it has the same problem that all the other circuit boards in the Mercedes cars have - cold solder joints due to the German regulations regarding the non-use of lead in solder. Almost all circuit boards can be effectively repaired by resoldering the connections with a good quality 60-40 solder. I have done several myself.

Regards,
Richard Wooldridge
'82 300D/4.3L V6

mctwin2kman · #8 10-13-2004, 12:01 PM

W203's have had many issues with lamps and lamp failures. Check out a W203 specific forum for more info. You could try mbklasse.com/forums/ for info from those guys. Very knowledgeable and all own W203's. Mine has an issue where the license plate bulb keeps going out, but is not blown. It works most of the time then every once in a while it does not and I get the MFD telling me I have a Malfunction and the left license plate light is out.

mpolli · #9 10-13-2004, 12:03 PM

Richard,

Where is Battleground? Never heard of it. But I don't get out much, usually home fixing my Mercedes. When did the Germans stop using lead solder? I just repaired a cold solder joint on my 98 C230 a couple of weeks ago. Psfred has a thread going now (with no replies) that I was thinking maybe a cold solder joint on the box the reads the cam signal. But his is a 85 I think. Were they using lead back then? Better get used to the non lead solder as the whole world is changing to it next year.

Mike

AusMBtech · #10 10-14-2004, 05:13 AM

Yes, this is a common problem.

You'll need to get 2 "modified wiring harnesses" (something you hear alot about with new benzs

) It just plugs inbetween your tail light and the existing harness to give an extra voltage drop before the tailights.

It seems to be working on cars with them fitted...................for now

mpolli · #11 10-14-2004, 11:56 AM

Why do they need to drop the voltage? Are they using "funny" lamps?

Mike

AusMBtech · #12 10-15-2004, 07:53 AM

All the globes are built for 12v like they always have. The voltages to most globes are 13v. Now we're seeing 13.5-14v in these circuits. This shortens the life span of these globes. It shouldn't be a problem but it is occuring in some models. The modified wiring doesn't drop the voltage by much. Newer 203's don't need the wiring mod, they aren't expereincing the fault.

ROGER E. · #13 10-17-2004, 12:07 AM

I am absolutely astonished at some of the crackpot "solutions" for this bulb eating problem. I just happen to own an '01 C320 which has never burned ANY bulb out after 3.5 years. BTW, I assume you don't live in the US since your car would still be in warranty if you did.

The suggestion about overvoltage doing it can be dismissed because there would be far more problems than just a dead lamp. In any case, 13.6V max is normal when charging in all cars. I this were my car, and knowing that the left side lamps are failing. I would find the ground termination for that lamp assembly. That's the brown wire in the plug on the bottom of the lamp which disappears into the wiring harness descending downward behind the trunk liner. I just looked at my own car to verify this. It's likely that the ground wire is terminated on a ground stud somewhere nearby (a current flow diagram would tell you where, if you had one) and it may be loose or corroded (hard to believe).

This will produce a varying current flow which will kill the lamps in no time. Halogen headlight bulbs are particularly sensitive to high or varying resistance grounding, by the way. Other end of the car, of course.

You can remove the trunk liner panel behind the taillight to eyeball the plug but the entire side panel may have to be loosened to follow the harness very far.

I'm a bit surprised that the dealer tech didn't think about grounding. Or am I?

psfred · #14 10-17-2004, 01:16 PM

Ah, the joys of excess computing power.....

The cruise control circuitry is grounded through the stop lamp filaments. When the lamps are on, 12V (nominal) is applied to the ground of the control circuit and since there is no longer a voltage differential, it switches off.

Very slick, if you ask me, and nearly failproof as the CC won't work if the stop lamps aren't good. Only problem is occasional problems from bulbs with too high a resistance in the filament causing erratic operation of the CC.

blowing bulbs means either the bulbs aren't strong enough or you have an overvoltage problem -- I've never seen an automotive lamp fail in normal 13-14V service when the correct type was used. Makes me think the specification is wrong for the lamps, this isn't rocket science!

Peter

bender · #15 11-06-2004, 09:43 AM

My dealership replaced the wiring haness for two lights that blew out. They said it was a warranty issue and the harness was the resulting "upgrade" to the problem. This was in august. "So far", it has not happened again.