So I've searched many forums and have found about 10 threads about the same problem but none have solutions. Problem: my taillights went out the other day but the third brake light still works??? I'm gonna grab some fuses and bulbs this afternoon. I checked the fuse and it's fine...but might as well grab a pack and switch it just in case. Could it be the brake light switch??? Are there any relays that are tied only to the rear brake lights and not the third or is it possible to burn out half of a relay or brake switch??? The car is going to get replaced this spring...probably a newer a4. This one has many electrical gremlins and about 200k and it's a 1997. Mechanically it's perfect...never had a motor issue other than replacing the coil packs. Oh and the turn signals/reverse lights/ect. all work like they should. I'm stumped...please help. Thanks

 

That sounds like it has to be a switch issue, unless you've severed a wire and/or ground somewhere.

Check the wiring at the brake lights with a DMM or a test light. If you're not getting juice to the brake lights, then you know it's prior to that.

I'm guessing it's the switch though.

Keep us posted.

 

UPDATE: I tested the brake switch and it came out ok. It ended up being the brake light bulbs. I'm still not sure if they shorted out or what was going on but replaced both rear brake lights and all is well.

 

Good to hear!