I keep getting an error about my tail lamps. I have replaced the bulbs and the plastic housings. It lasted about 20 miles and then **Beep** again. I am at a loss as to what next. It is really irritating.

 

Do you brake lights light up?

This may sound odd, but on my car, the right bulb burnt out, and I went to the Auto Shop and purchased a replacement and put it in. I went to drive off, and the warning came back, and the light on the other side had burnt out right there and then. I had to replace both sides in the same trip.

 

I just had this problem on a 1998 E300 I purchased about 1 week ago. The RH rear brake light was out so I put a new bulb in it. A few days later I got the "lamp defective" message in dash. It was the back RH brake light out again. Pulled out bulb and the filaments looked fine but did not have my voltmeter on me at the time to check it. Bulb socket lloked fine too as well as the contacts on the socket and the housing. I was right up the road from auto parts store so I picked up new bulbs. Put in the new bulb and it wouldn't light up. Messed around with in for a few minutes and found that after I turned the socket all the way clockwise, I had to back it off to the left just a hare. Been working fine ever since. Dielectric grease also helps. If it starts to act up again too soon I will switch over to "face lift" taillights or LED assemblies.
Hope this helps
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On the other hand, if the socket/PC board is melted due to poor contacts, and if you hare handy with a good solder iron, just solder a wire from the bulb tip to the PC land and you'll be good for 5 years or so!

Otherwise, buy a new lamp assembly for $100 !

 

mine was the pigtail and plug at the bottom of the light board. the contacts were a little rusty and loose, even if i adjusted it to stay on it would wiggle loose down the road. my solution was to insert a piece of plastic into the plug to jamb the connection to be wiggle free.

 

I also had the repeating Lamp Defective message. It was always the right rear stop light. I finally gave it a close inspection and the metal plate the bulb holder twists into had a hole worn (burned?) through it where one of the bulb holder contacts rests. My solution was to solder up the hole and reinstall the same bulb and bulb holder. Well, it worked! It's been over 2 months and no more messages. Hopefully, it will last.

 

Yeah over time that board melts and when you replace it with a new one say the right one, and the left one is still old but working. The elecritical system sends more power to the older one because it requires more energy to light, thus burning it out soon after you had replaced the right one. Same goes with headlights. It's not just mercedes it's all car makes. I replaced the whole light unit on both sides when it happened to me. 1 there a hundred dollars and take 5-10mins to replace. Only like 3-4 bolts and 2 you get brand new nice shiney plastic.

 

As Sparky says, back the bulb socket off a little. I did that based on recommendation of another owner and problem never returned.