Horn Wiring Diagram Help
 

See attached wiring diagram

I have a 2011 A4. The horn is not working when pushed but works ok if I send power directly to the relay. Have replaced clockspring, no luck. Can someone explain the wiring flow to the relay

1) At the steering column, is power coming into the two black lines with NCA (No Colour Assigned) or is power coming in at pins 8 & 9
2) What is the Computer Data Line System?
3) Is power coming in at pins 14 & 15 at the Electronic System Control Module (I believe this is the J519 module)
4) I have connectivity from pin 29 to pin 2 on the relay

Any help is much appreciated