Brake lights coming on when car is off


I have a 91 Acura Integra LS, automatic. Sometimes my brake lights just come on and off when the car is off. I hear a clicking noise coming from the shifter. This is causing my battery to run down. Any ideas?


This is just a guess but since the warning lights are used in the alternator field circuit I suspect that a blocking diode has shorted. To see if this is correct try disconnecting the small wires on the back of the alternator and see if the problem clears. If so, replace the alternator. Be careful with the main output lead of the alternator as it is always hot to the battery. Don’t ground that lead or touch it to anything if you remove it.


The problem might be with the interlock/brake light switch above the brake pedal. This switch always has power to it because the brake lights work whether the ignition is on or off. This switch also controls a solenoid at the shifter so the transmission can’t be put into gear unless the brake pedal is depressed.

If there’s a problem at this switch, either because it’s out of adjustment or defective, the brake lights can come on and you’ll hear the interlock solenoid click.