2012 Q7 - Trailer brakes not working - 02539 - Terminal 30 Defective

[vtraudt]

1 Fault Found:
02539 - Terminal 30 from Control Module
014 - Defective

Had been working fine for over a year.

I have checked the fuses in the trunk (rear right).
I have swapped the module.

Sometimes I can clear the code and then trailer brake works once, but then code comes back and not working.
Recently could NOT clear code (comes right back) and brake controller is not working.
Contoller is Tekonsha Prodigy P2.

I learned that "Terminal 30" is synonym for 'unswitched power' (i.e. permanent battery power).

Any tips, suggestions, ideas how to troubleshoot?

[ozdi]

Check the fuse for power supply to the trailer brake controller. Then check if the trailer-brake controller receive the "braking" signal from the trailer controller module J345. Then check the trailer socket.

[vtraudt]

Check the fuse for power supply to the trailer brake controller. Then check if the trailer-brake controller receive the "braking" signal from the trailer controller module J345. Then check the trailer socket.

The problem was an 'on/off' type. Sometimes brakes worked, sometimes not.
At the end of the day I found a shaved wire, assume sometimes shorted to ground.
No blown fuses (so short not bad enough to blow fuse, or tell the controller SHORT).