Just working on this retrofit now to discover that maybe not all Audi A8 D4 steering wheel column looms are the same. The main harness connector to the Steering column control module I have doesn't have pins 1 (GND) & 2 (12V) wired.
A question to those who have done this, was this also the case for your install? Was pin 1&2 wired already or did you just replace fuse in fuse carrier 2, Fuse 8C to a higher rating?
It looks like the steering wheel heating element can pull power from other pins (3 for 12V & 10 for GND) but it seems like the pins its meant to pull from (1&2) are a heavier duty so not to over load 3&10.
Also
the steering column switch - does that single signal wire go to pin 1 on that unused connector on the steering column control module?