2011 VW SEL no TCM communication

Hi, I was working on horn in my daughters 2011 Jetta SEL
I hooked up 12V from battery to one terminal on horn and hooked one of cars horn wires to other terminal. No horn
I then hooked other horn wire from car to the terminal and still no horn activation
I now have no communication code U101 no communication with TCM and shift interlock doesn’t work, low tire and CEL.
Does and I believe what I did was back feed 12 volts through the relay and into BCM Central Control Module ? It’s the only module I see connected to the horn circuits.
I have all fuses good and I have 12V constant on 2 pins of TCM and good ground there.I’ve been a mechanic for most of my adult life with GM (not now) I tested for ohms on pins 6&14 of DLC. No reading. I’m lost I’m willing to pay for help but not letting some dealer or something spend hundreds of dollars guessing. I’ve never had anyone work on any of my cars. I will gladly pay for your help and Please help if you can. Please. Thanks. Rick
518-225-3467
Rdemarsh60@gmail.com

rick.demarsh wrote:

I hooked up 12V from battery to one terminal on horn and hooked one of cars horn wires to other terminal. No horn
I then hooked other horn wire from car to the terminal and still no horn activation

So to be clear, all your testing was done at the horns themselves, correct? If so, I can't see how you backfed anything. If your Jetta uses a horn relay, then you were on the load side and not connected to any modules. If it uses the BCM, then 12V is on the power feed coming from the BCM anyway. I attached the horn relay diagram for reference:

I have all fuses good and I have 12V constant on 2 pins of TCM and good ground there.

From what I can tell, you should have power on three pins at the TCM the key on. Pin 3, 27 and 28. Ground on pin 1 and 1. Power on pin 3 comes from fuse #20 in the underdash fuse box, left side. That fuse also happens to power the shift interlock solenoid. I know you said your fuses are good, but I'd suggest rechecking fuse 20 first. Check that it didn't get pulled and put back into the wrong slot in the fuse box.

Yes, only thing I did was mess with damn horn wires and immediately after wouldn’t shift TCM communication.
I will definitely recheck fuses, as for relay that’s what was baffling me. How to heck did I do anything to a modules can bus. Thank you sir I will recheck everything and let you know.