Hi,
The other day the computer in my 2004 Audi A4 Avant 3.0L Quattro told me the Brake Light is malfunctioning. I determined it was the driver's side tail light and proceeded to take off the light fixture/housing. I look at the tail light bulb and it seemed fine, the filament was not broken or anything. I tested the other bulbs in the tail light socket and they don't light up. Then i took the bulb from the tail light socket and put it in the other 3 sockets and it lights up. So the bulb is fine.

How do I figure out what's wrong with the socket and how to fix it since it's not the bulb???

 

Anyone have an answer on this? Thanks....

 

I am not going to be much help here. I do have a questions though. Do the turn signals or four ways work? Is it the tail light and brake light not working or just the brake light?

First thing I would teat is if the socket is getting power (tail light, signal, brake). Most likely you will need to trace the wiring to look for a break somewhere. Not sure if there is a fuse or control module that would affect only one side of the car.