Tackled my son's 735i brake light problem this weekend. His tail light were going off and on for no reason. Took out the infamous mustard relay and examined the circuit board closely. Now that I am 53 years old my best closeup vision is without glasses. On close examination of the board I notice multiple soldering joints that were cracked. I used braided copper wire to remove all of the old solder and a good electronic solder with flux to resolder. Came out real nice. Easy job and took less than a half hour. Now on to his aftermarket amp, Looks like he cooked several capacitors. Luckily for me there is a great electronics outlet close by