I am having the same problem on a 2001 X5. My rear right brake light keeps going out. The tail light housing seems brittle, and the old socket was slightly melted. I bought a new socket at the dealer ($27 rippoff) and a bulb, but the problem persists.

My question is, regardless of the fix proposed, grounding the circuit, would replacing the entire tail light with the newer version (04 and up) fix it?

Im sick and tired of beeps and messages...