mr.spoolin

I have a 1997 audi a8 quattro that i had just purchased, when i had bought the car it had a brake light out so i figured easy fix. so i went in and got a new brake light, when i replaced the bulb everthing worked great for a day then the next day, when i apply the brake a warning light comes on that i have a light out but all the lights are in working order.

Then when i turn on my parking light and or headlights it lights up all of my parking lights and all of my brake lights with out me applying my brakes. I had a couple friends think its the multi function switch in the stearing wheel but i am not 100 percent sure.

silverd2

I would start with a close inspection of the socket itself (where you replaced the bulb) for shorted contacts and check all wires/connections on the light housing.
Also leave the replaced lamp out, while you test the lights again, to see if the new abnormal behavior is still present.

Kneale Brownson

I'd check the bulb first to make sure it isn't either in place incorrectly or shorted internally.

Did you buy a good quality bulb or a cheapo from Walmart? It can make a difference.

If everything else is OK, I'd check the bulb holder assembly for corrosion/shorting. I once had a VW Jetta that the lights would go crazy on because of a crossover in current in the bulb holder assembly.

mr.spoolin

i did buy good quality bulbs, and i checked all sockets, bulbs and still nothing. i also tried disconnecting (from the clips)all the lower tail lights and nothing changed.

When i messed around a little more i noticed that when all of the lights are off and i apply the brake it also lighs up my front parking lights as well.

Kneale Brownson

I'd check for continuity between the brake bulb sockets and the other sockets/circuits in the bulb holders. And between the posts in your new bulb. Also check the grounds in the tail light area. Somewhere you are crossing over circuits.

silverd2

I have to agree with this...just doesn't sound like anything that a switch or lighting module (relay) would do...it screams of a wiring problem.

mr.spoolin

ok i have figured out the brake light ordeal, it was a bad ground in the trunk,thanks everyone.

i have one more question, when i apply the brakes when the headlights r off it lights up my parking lights in the front and back it really doesnt bother me it would just be nice for it to work correcly. I was gonna see if u still think its a socket or a jumping circuit?

silverd2

Yes...obviously NOT normal and still sounds like a wiring or socket short.
It "may" be possible, but have never heard of a lamp control module (relay) failing this way...BUT it's the ONLY other thing that the brake lights and parking lights have in common.
And really don't think it's possible for the light switch to do this...totally separate from the brake light circuit.