W212 Facelift rear LED fault

[sgtshultz777]

There is no need to take the rear lamps a part. Here is a way how to fix them. This lamp is from LHD car and this lamp is from left side "view from behind". Those should be pretty similar in RHD and LHD cars as


far as i know.
You can cut these "service holes" where you get access to these three connectors witch usually are the origin for the problem. Just solder with tin those three components and you are good to go.
I used dremel to cut those service holes and vacuum cleaner was sucking the plastic chips whole time i was cutting, inside the lamp remained clean.
You can glue the plastic peaces back on it or just use some strong tape to cover the holes.
The whole job took about 45min and i saved 350€


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anyone know what size these resistors are?

I need to order a couple.

 

[silver1011]

I don't think you need to replace the resistors, just refresh their solder / joints...

 

[avantdi]

There is no need to take the rear lamps a part. Here is a way how to fix them. This lamp is from LHD car and this lamp is from left side "view from behind". Those should be pretty similar in RHD and LHD cars as far as i know.
You can cut these "service holes" where you get access to these three connectors witch usually are the origin for the problem. Just solder with tin those three components and you are good to go.
I used dremel to cut those service holes and vacuum cleaner was sucking the plastic chips whole time i was cutting, inside the lamp remained clean.
You can glue the plastic peaces back on it or just use some strong tape to cover the holes.
The whole job took about 45min and i saved 350€


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Did this fix this morning. Took about an hour. Thank you for this great post.

 

[Nestu]

There is no need to take the rear lamps a part. Here is a way how to fix them. This lamp is from LHD car and this lamp is from left side "view from behind". Those should be pretty similar in RHD and LHD cars as far as i know.
You can cut these "service holes" where you get access to these three connectors witch usually are the origin for the problem. Just solder with tin those three components and you are good to go.
I used dremel to cut those service holes and vacuum cleaner was sucking the plastic chips whole time i was cutting, inside the lamp remained clean.
You can glue the plastic peaces back on it or just use some strong tape to cover the holes.
The whole job took about 45min and i saved 350€


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just did this fix, about an hour of work, thank You! i did the right side (passenger) lamp tho, it is mirrored if anyone wonders (yes i flipped the photos horizontally... LOL)

 

[badkarmacreepin]

Came here via Google looking for info about the dim tail lights on my 2016 E350. Posting because after following the instrux, via the first post about the 'service windows' and the later on post re: a gas stove (I used a lighter) + Stanley knife, the whole assembly now works like a f'ing charm!! Ftr, the three bolts holding in the tail light are 8mm...not sure if that was referenced or not.

Way to be MB community - saved me ordering a new tail light assembly, and worst case, a truckload of cash at the dealer!

 

[repairer]

(A bit O.T.)

I was about to suggest the solution that aheinionen described with pictures.
Have done this a few times with some 3rd brake lights that when mounted
on the rear boot suffers from water ingress due to bad/dried up gaskets.
MB does not sell the gasket as a separate item as it is "pre-glued" to the
red plastic. After repair and using conformal coating urethane lacquer on the circuit
board, the assembly has been re-fitted and sealed using thin curing silicone.
(Yes - be careful when selecting brand since some of them can dissolve the paint)

It could be a good idea to replace the surface mounted resistors with axial
versions (of equal power rating) simply because they withstand thermal
stress better. (Mount them in an "S"-position).

Even better info. Do you remember the details of the three surface mount resistors? Where is the "S"-position? My tail light on E250 starts to play. I try to repair it myself.

 

[Uky]

I am sorry but I do not. In my case (a CL500) it was some of the thin copper traces on the PCB that had corroded away.
Surface monted resistors comes in different sizes. Most of them has the resistance printed on them in very small text.
Like "102" for 1kOhm, "391" for 390 Ohms, etc. Physical sizes are most often described using inch-based dimensions
like "1206", "0805", etc. where the first two digits represents the length in mills (12 = 120 mills or about 3 mm, 06 = 60 mills or about 1.5 mm)

If you manage to fix the tail light, I suggest also spraying the PCB with some conformal coating afterwords.
Do not forget to mask the connector...

And also pay attention to the mechanical lock. If the water had reached the tail light, it may also have reached the locking
mechanism. Since most people never use the key to lock the hatch, the mechanism seldom gets excercised.

 

[repairer]

I am sorry but I do not. In my case (a CL500) it was some of the thin copper traces on the PCB that had corroded away.
Surface monted resistors comes in different sizes. Most of them has the resistance printed on them in very small text.
Like "102" for 1kOhm, "391" for 390 Ohms, etc. Physical sizes are most often described using inch-based dimensions
like "1206", "0805", etc. where the first two digits represents the length in mills (12 = 120 mills or about 3 mm, 06 = 60 mills or about 1.5 mm)

If you manage to fix the tail light, I suggest also spraying the PCB with some conformal coating afterwords.
Do not forget to mask the connector...

And also pay attention to the mechanical lock. If the water had reached the tail light, it may also have reached the locking
mechanism. Since most people never use the key to lock the hatch, the mechanism seldom gets excercised.

Much appreciated. Thank you very much!