The brake lamp failure light on the dash lights up on my 89 240dl when I have the headlights on, and I push the brake pedal, or when I push the electric window switch up. All the brake lights are working fine, it doesn't light up when the headlights are off. So, I was wandering if someone had access to the wiring diagram, and could point me in the right direction. I think it must be in the head light switch, but more likely a ground in that circuit.

 

or even more likely, one of your front corner lights are out.

 

Ahh, good thinking. I don't think we checked the front of the car, just the back. I thought the light on the dash was for just the brakes.