14th Jan 2012, 03:41
I have a 1999 300M. It had the same problem; the brake lights would not turn off, even when the car was off. It's just a plastic switch that goes in the back of the brake pedal. Less than $20. Easy to install. The switch has like a little piston that goes in and out. Just make sure you don't push the piston in all the way with your hand. If you do, it will not work. The piston only supposed to go in as far as your brake pedal goes. Once you plug in the switch, it's a square shape, you line it up and turn it clockwise to lock it in place. Slowly release the brake pedal so it can calibrate the new switch.
25th Aug 2014, 14:50
I know this is a long time after the original post, but I have a 2004 300M and had the same problem. Turned out to be the brake switch that the brake pedal controls was going bad. Had the switch replaced and haven't had a single problem since.
11th Sep 2011, 21:57
Please!!! My car is having the same issue, HELP!