Anyone have an idea of why my third break light sometimes works (all LEDs light), but most of the time it does not work and the break light warning comes on, what could possibly cause this,is it common? Any suggestions would be great, thanks.

 

Our bmw does the same thing with one of its brake lights. It is obviosly not the bulbs, the wires seem to always be receiving an appropriate signal so that leads me to believe our problem is with the plug or contacts. Since I don't drive the bmw and he doesn't seem to be motivated to fix it, thats as far as we have come. On my old Volvo 850 I had several intermittent bulb failure warnings. If I shut the trunk to firmly it would say a bulb burned out, hit the taillight and all was working again. In the volvo it ended up being the plug that connected to the back of the taillight assembly. There were loose wires going into the plug. I simply removed the wires/clips from the plug and put new ends on them and slid them back into the plug. All was well, I could go back to slamming the trunk shut with no problems.

 

I tested the wire at a time when it was not working and it is reciving a signal, it's been working for the past couple of days, im going to replace the end plug and see if that works, thanks for you suggestions.

 

If slamming the trunk and banging the light causes it to fail/turn on, I would suspect a bad ground. I can't remember if the rear socket in my A6 was metal, but if it was, then there may be enough corrosion where it inserts into the light housing to prevent a good ground. If plastic, then I'm wrong.

 

^ agreed...it is plastic in the socket on the A6, so check the ground wire. It will be a common wire tied to the rest of thebrake lighting system.

 

ok great, thanks