rear light/ brake light... circuit meltdown?
 

Has anybody seen this? getting lamp fail so checked the lights, everything works but my first clue something was up that the right taillight assy was not as bright as driver side, then the whole assy failed. Got home, pulled the plug out and TADAA....now can someone give me a explanation on what,why...wtf.....

Probably this:

https://5series.net/forums/e60-discu...lights-135162/

https://5series.net/forums/e60-discu...-117069/page2/

if you want to prevent this from happening, you need to run another ground wire to chassis. the stock ground(brown) wire is undersized.

My 2008 530d is booked in with BMW on Tuesday to have the wiring loom replaced for free under their 'campaign'. The rear drivers side cluster is out (all lights) It was bought privately and is well out of any warranty. I'd recommend you call BMW now.