I've been getting the bulb warning recently but it was intermittent. This weekend I was following our X and noticed the RR brake light was a lot dimmer than the left. Irritating to say the least. So, I did a forum search and found the rear brake circuit board fix thread. So this morning, I removed the RR housing and the bulbs and there it was! The small burn hole in the circuit board. Took the Dremel and cleaned it out, resoldered and smoothed the patched area, reinstalled it and it works! The hardest part was removing the tail light housing. Had to use a small 8mm wrench, and lots of patience, on 2 of the 3 nuts because the sub location makes the removal more difficult. Thanks to everyone who helped contribute to the thread on this topic. You guys are the bomb!

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'03 Carbon Black M5
'04 Silver X5 4.4
'04 MB SL500