So I was in replacing a bulb today and noticed that along the bottom row of lights, there were: [Driver's Side Rear]

from left to right

Tail and Brake 2 stage light, tail light, and then another bulb similar in size to the tail and brake combo.

On my Passenger side rear, this third bulb was missing. I tried all combos of brake, reverse, turn, hazard and couldn't get this third light to light - and the bulb is fine.

Question is what is this third bulb for?


Thanks

KB

 

I could be way off here... but could it be the rear fog light? only the driver's side taillight has one, so maybe they just left the socket empty on the passenger side one?

 

It is the rear fog light, they intentionally leave it bulbless so it doesn't look like brake lights.

 

def the rear fog light. dont really need it but it is there just incase

 

I replaced my brake light last week on the left side and today i have to replaced the other one on right side.Im just curious why i have 5 different lights each side? one bulb is not working on both side and i want to replaced it but i don't know what im gonna say to the store(my car is Audi A4 2002) Please some one can tell me what's the history or purpose of those 5 lights...coz i only know about two lightsThanks!!!

 

It is indeed the rear fog light - that is left bulbless by design. But even after I put in a bulb there - I couldn't get it on with the rear fog light switch.

Anyone know the trick to get this thing on?