Intermittent rear brake light issue
 

It's not a big deal but my passenger side rear brake light works intermittently. I get the warning on my dash so I go to the back and adjust it and it works again. A few days later it happens again. I tried to adjust the prongs on the socket so it pops out more thinking it is a contact issue but it doesn't seem to work. What should I do? Buy a new socket or bulb? I doubt it's a bulb since it's intermittent. Is this an electrical issue?

Thanks,

Scott

I had the same issue some time ago and was driving me nuts. I bought some electrical cleaner liquid I think from Autozone and cleaned the contacts well and plugged back in and it has been fine ever since.

Most likely the problem is the conact area where the buld fits has been "burned" away due to arcing. BMW uses a poorly designed bulb "busing" system in which the bulbs can move or otherwise vibrate within the holder. It causes the contact points to become separated and they'll arc when a voltage is applied. Over time it will literally eat away the metal. Very common issue which is easily fixed.

Remove the taillight assemblies. Take out the bulbs. Take a close look at the round metal contacts and see if you can find any areas where the metal busing looks like it was melted or pitted. Clean the area and use some good quality solder to fill in the holes/pits. Sand, grind, or file smooth and flat with the metal. Reinsert the bulb and reinstall the tailight. Problem solved.

Best solution

Yup, I concur. Same thing happened to my X, did that and all has been well for over 2 years.

i agree as well
 

I fought and fought. bought new bulbs etc. i finally pulled out the tail light assembly and there it was, a small hole. i took some solder and my soldering iron and patched it right up. ground it down with my dremel tool and no trouble since. what, other than a bmw, would have this kind of crap go wrong???

Exactly my problem, except the arcing has caused it to melt the plastic around the contact. It melted just enough that the it was defroming the contact and the bulb would not stay seated. I replaced the taillight 6 months ago and it is starting to happen again on the same socket.

I am thinking of replacing them completely with an LED retro-fit. My thinking is that it might not get as hot.

There is a retrofit kit from MB that gives the lights a dedicated ground wire, only costs $20 a side.

Do you have a link to this item?

Unfortunately, I am probably going to have to replace my tail light (again), as it has melted around the brake (lower) bulb. Since I will probably have to drop another $90-100 on a used light, I was thinking about doing the LED upgrade. I'm not sure if that is solving my problem (while gaining an aesthetic upgrade) or just pushing it onto a new system.

Mercedes Benz part number 164-826-00-07, you will need 2 kits.