"Right Brake Light Failure" but it works!!!!

[opnairst]

My 2004 9-3 Aero tells me that there is a 'right brake light failure' but the right brake light works just fine... ?? what's up..

[Digger]

My 2004 9-3 Aero tells me that there is a 'right brake light failure' but the right brake light works just fine... ?? what's up..

The car spends about a split second testing a light circuit, actually heating the filament happens slow enough that the human eye can see the filament change from cold steel to white hot. The car might send 12 volts down the line to test the circuit, but it only sends enough current to test the circuit, not enough to light the bulb. When the brake light switch sends 12 volts down the line it sends enough current with the 12 volts to light the bulb. Electricity likes to take the shortest / easiest path to ground, but it will take any path it can find and with enough current / power, it will cross a dirty ground, back flow through another bulb filament, even jump a spark to steel if that's the only available path.

The car computer has tested resistance and decided that you have a bad circuit, if the computer is right the brake light bulb will eventually figure this out too.

[opnairst]

Thanks, I will try to replace bulbs with new one and clean connections (just bought it and it's been standing for a while) , will advise..

UPDATE: Works like a charm.... pulled the old bulb, cleaned out contacts, put in new bulb and no more bad messages... Thanks