[Help/advice] Right Rear brake light problem - Mercedes SLK R170 230K


When I hit the brake the brake lights work, however the right brake light doesn't. Lamp ok, fuse ok, light unit ok.

I live in Holland and I'm a big fan of the show, for about half a year now I own a Mercedes SLK R170 230K (the one on the header is mine). Recently an issue with only the right brake light has occurred. I was wondering if anyone could give me a pointer.

When I hit the brake the left and center brake light work, however the right brake light doesn't.

I first replaced the light but that didn't fix the issue. Then I took off the lamp unit and checked it for corrosion of which there was none. So I decided to do some measurements. When I manually plug the unit into 12 volt it works just fine. However when checking if the connector supplies power when I tap the brake, I found out, the car is just not providing power to the brake light wires on the connector going to the lamp unit.

I also checked the fuse and replaced it just to be sure. I'm kinda out of ideas of what to do next and figured maybe anyone would give me a hint.

I'm currently thinking a broken cable, (I've never touched them before so I don't expect this to be the case) or maybe the breaklightswitch? this would be weird since the other brake lights do work.

Kind regards!


Comments (2)
No. 1-2

Hey Scotty, thanks for your fast reply! I think that's a great idea and I think I'll try to execute it this weekend! Again, many thanks. I didn't expect you'd have time to actually answer so many of your fans and their questions. I really enjoy your videos!



realize that insanely designed merc uses a set of small computer modules just to run the lighting system. To fix such a system a STAR tester is needed to analyze and figure out the faults (which could even be inside the computer modules.) I'd never buy one, but you could run power from the brake light size that doesn't work to the one that does work, I do that all the time in those crappers and it works fine if you rewire it cleanly and cut the old wires feeding the bad side off so not to feed power into a shorted out section