Dreaded rear lights going dim and burning smell

[Diamondw204]

Well after 18 months of trouble free motoring I noticed the rear lights were really dim and smelt burning
you guessed it both earths burned out connectors melted rear lighting clusters burnt
ordered two clusters and connectors from eBay shop Mercedes Newcastle £37.10 each
got 21amp brown cable ,crimp round connectors and small button head bolts And nylocs
drilled and bolted round connectors to light clusters,replaced connectors and earth pins
connected to body earth point.
nice bright lights and no further problems

 

[John]

How old is the car?

I don't think I've ever suffered from duff earth connections even when I had some ancient motors.

I do remember seeing a few cars around with the whole cluster dimly-lit (normally MK4 Escorts actually a long time ago) but not seen that for a while.

 

[190]

This is a known fault with the W204 and a common failure in the US where they presumably never take their foot off the brake. I think it may even be a recall over there. I keep meaning to inspect mine although I'm hoping I won't find a problem as since being aware of the issue I avoid keeping the brake lights on when stationary. The inadequate earth can't cope with the total current when rear lights and brake lights are on at the same time. It's a rather basic thing to get wrong. You would think someone at MB might have a grasp of ohms law.