In need of some help guys. For the life of me I have spent a good hour trying to google, youtube, and on here on finding which bulbs control what for the rear light cluster. I thought I had a bulb out and now I am trying to find out what each of the 4 bulbs do, but I can't find it anywhere. I looked in my manual and it just said to take it to a dealer, (thanks for that audi). Can someone please tell me what each bulb is for in the rear brake light cluster on my 2000 A4 Quattro 2.8L? Thanks a bunch.

 

I don't understand what you're asking. By "rear light cluster" do you mean the tail light? It shouldn't be that hard to determine which bulb does what by stepping on the brake, hitting the turn signals, and putting the car in reverse. Or do you mean the center brake light? In which case there is only one answer.

 

I found out what I was looking for. Took apart both brake light assemblies and found out that there isn't a rear passenger fog light, there is only the driver side fog light. Im never going to turn on the rear fog lights now because it definitely looks like you have a tail light out. Perfect reason to get pulled over by the police.

 

Yep, US law requires only a single rear fog light on the driver's side. The only time the rear fog light should be used is in very poor visibility situations like dense fog or a blizzard. Only one is used is to prevent confusion with the brake lights.