Voomon

Ive got an 07 A4 3.2 and yesterday while driving in the rain I had a dashboard warning light come on telling me the rear left brake light, tail light and indicator bulbs were out. When I stopped and checked they were all working fine. Ten minutes later it came on again briefly then went out and all the lights continue to function normally - where should I start hunting for the source of this? I was thinking it may be a bad earth connection in the tail light unit? Has anyone else had this happen...

John535is

The brake light switch under the brake pedal is a weak point and often the cause of intermittent brake light issues.
The good news is they are cheap ($25) and easy DIY to replace.
Make sure you buy genuine if you decide to replace it.