MK5 GTI Steering Wheel Controls or Horn Not Working

[Omerta11]

I’m happy to report it’s Finally Solved!!!

As I suspected, the wiring for the horn switch was wrong. As to why, I can only put it down to the guys that I got to install the Steering Control Module - they clearly had no clue what they were doing.

I analysed the wiring harness for the horn switch & airbag. Without a wiring diagram, it was hard to work out what was right and wrong. I looked online for a wiring diagram and couldn't find an exact match, but found some similar ones.

One wire looked to be plugged in the wrong connector lug based on its plug size and configuration, and another connector lug was bent out of shape. I fixed the bent lug, and looked closely at another lug on the opposite side of the unit where I suspected the misplaced wire should go - it was scored, so I made an educated determination that the wire in question had been plugged there previously. Plus, it looked like where the earth/ground circuit should be connected based on the similar wiring diagrams I was able to reference.
I took the plunge and wired it the way I thought it should be. Put it back in the car... and it all works!!!!

Car is back to normal - very happy, and satisfied I was able to work it out.

Totally furious at the guys that (incorrectly) installed the Steering Control Module...

Lucky for me, I had the time and (limited) expertise to work through the issues. Goes to show that when you want something done properly, you do it yourself - and with the help of this community!