1998 E320 right brake light Kept breaking for No Reason!
 

This smells like a design flaw of some kind. I've had the rear brake light circuit boards replace twice already. The rear right brake light keeps going out (the bulb itself is completely fine) but there's no light. Dealership couldn't find anything wrong and ended up replacing the circuit board. But after a few months, the brake light would go off again for no reason.

Does anyone have a fix for this? The dealership replaced the circuit board twice while the car was still under warranty. But i'm not sure if i want to shell out big bucks to get that board only to have the thing go bad on me in a few months time.

Much Obliged!

Mars

Its actually rather cheap, maybe that is why it fails so often. I have never had two on the same car though.

My 98 E320 developed a small hole (from arching) in the metal plate on the tail light assembley for the right rear brake light which created occassional lamp failure messages.

The temporary fix was to slightly turn the lamp socket so that it comes in contact with the good portion of the metal plate.

I might consider filling in the small hole with solder.

hi rjnonnie. that sounds like an easy fix. unfortunately mine wasn't solved using that trick. the bulb is good, and the contact point is there, but the lamp just won't turn on.

hi steve, do you know how much the board costs? if so, which part number is it?

TIA!

Mars

My 96-E320 has exactly the same problem. I occasionally get the "lamp failure" message because the right brake light would not come on during braking (the bulb is perfectly ok). The problem is solved most of the time by switching the 2 bulbs, or removing and reinstalling the bulb many times (sounds like a bad contact problem doesn't it?). Sometimes, you need a new bulb.

Lamp failure light
 

My '99 E 320 has the same problem. The lamp failure light comes on about once every few months. The right rear brake light does not work. When I check the light: the light bulb is fine. I have found that if I turn the light socket only halfway into the light assembly it will work fine. Eventually, from vibration, it slowly moves around and the problem occurs again. I have tried to bend the contact for a tighter fit and also have cleaned all of the electrical contacts.

I have exactly the same problem as Mike (MDARR), it seem as though the pins on the bulb and slots in the holder can result in misalignment of the contacts on the back of the bulb. Talk about rank engineering.

I tried a couple of different sources for bulbs, aftermarket stores and MB dealers; my solution is to swap the bulbs around and only partially twist the bulb in the holder until it works.

As an aside does anyone know why MB couldn't use the same bulb as the rest of the industry?

Good luck,

Peter

the 2 little metal stubs that protrude from the base of the bulb is placed at an angle that makes it impossible for industry standard bulbs to work on these mercedes sockets

MB 'Quality' joke
 

Electrical connections and systems on MBZ are a joke compared to the rest of the world. lead fuse elements like pre WWII, direct bulb contact on circuit board foil leads, biodegradeable wiring insulation, etc.

This stuff is like keystone cops designed it and incorporates none of the performance improvements the rest of the industry has developed. I guess the feeling at MBZ is 'if we did not think of it--it can't be any good.' Only problem with that is all the great engineers of previous years are gone and 'computer based' design doesn't ever capture field experience like good ears used to.

The MBZ computer controls system is extremely sensitive to faulty connection. They did things right when they started with ABS in the very early 80's, but after about 10 years things went to pot. Only worse since then as they increase complexity of the computerized control systems so much that usually something is always not working. The replacement 'boxes' are tremendously costly because they are special purpose and low volume--every system has unique computer. Chrysler has 1 computer and a lot of different software programs.

I put some solder on the bulb. It work well until now almost one year already.

I have the same problem...
 

I find that the problem is in the socket. if you push in the socket it will light. my short term solution was to put a tennis ball on the socket and then close the cover. Puts just enough pressure on the socket... I'm thinking of ways to thicken the clips that pull the socket in...ideas?

Still can't get the right brake light to work. This is getting rediculous. I beefed up the solder point on the bulb, plugged it in securely and then added a tennis ball to push it in for good measure. Nothing is working!!

You might have better luck tracing the problem with a multimeter. You can hopefully locate the problem area and repair or replace the bad part.

As I mentioned before, the problem I had was a small hole in the metal plate that the lamp socket (should have) made contact with. I didn't notice the problem until I dissembled the tail light assembley.

Thanks for the input, RJ. Never was any good with the multimeter. Not sure which switch i should choose for the current test. Any ideas?

I would use the DC Volts setting to trace the voltage starting from the wire going to the tail light assembly and ending at the lamp socket. The black wire should be connected to chassis ground and the red wire to measure the 12V DC volts.

You could also get a circuit tester (from an autoparts or hardware store) that has a built in light instead of using a multimeter.