BTW, I took my VW Touareg in 3 weeks ago for a towing brake module that was non op. I was not getting electrical brakes to my Prodigy RF brake controller, and I was not getting 12V from my tow vehicle to the Trailer battery.
I ran a scan with VW Audi Group specific software to trouble shoot the problem. Software and cable said the brake control module had failed. Seems it failed Jan 16th, 2015 on my way to Quartzsite, when I first hooked up the trailer, it showed as "failed connection". Logged, timed, everything. Unit failed in 17 months, and not even 5000 miles of trailering.
Checked fuses, all 5 of them were good, checked main T-30 fuse (40 amps) and it too was good. Pinned out the voltage to the module and had 12V at input side of the module.
Took it in to VW, they ran the exact same diagnostics tests and pin out tests that I did, after bringing them in the print outs of my scan and proclaiming the towing brake module had failed. Took them 4 hours of trouble shooting.
They told me they ordered the part, it was covered under warranty. Part would be in in a week, had to be ordered from Germany.
Part was not in in a week, and when it did arrive, they told me the tech that worked on my car was on vacation and it would be another week.
Two weeks later, this Wednesday, I take the car in again. Tech is working on it and service writer asks me if I installed the trailer controller. I answered yes I did. He told me then that I would have to pay $400 for the new trailer controller. I told him I'll take my car now, thank you. He said VW wouldn't cover it unless they originally installed it. I told him the installation didn't fail, the part did.
I told him the module is plug and play, proprietary plugs, and it was not the installation that failed or needed warrantying, but the part why were you doing the labor and trouble shooting under warranty, but not the part?
Good luck VW dealership for getting paid for troubleshooting from corporate, I'll buy the part from a junkyard if you won't warranty the part, and take the 10 minutes to R&R the plug and play part.
This homie don't play that game. I didn't pay a cent. Shop isn't going to get paid for labor either. Part of that 3 year /36 month bumper to bumper warranty.
Service writer told me they had to order the new part, to compare and test against the old part to compare outputs. Service writer told me 2 weeks ago, it was all covered under warranty, part and labor.
Drag it out 2 plus weeks to make me feel thankful I am getting my trailer controller fixed so I can camp this summer. This is how they break you down, and squeeze the money out of you, the wrong way. Not me.
This VW dealership is located in LA county in the high desert. ;-)

proprietary connector plug ins.

Popped the cover off, nothing on the circuit board appears fried or burnt. Maybe a bad solder connection or a bad chip...