Audi Multifunction steeering wheel

Schematics:

 

Fritzing file. 

Steering wheel with electronic for MFSW (4B0 419 091 BB)

control unit in steering wheel

connectors from left: power, button inputs, output

Control unit for MFSW (4B0 907 487 E)

Based on MCU pins used, comunication is CAN @ ~17000kHz 

looks like control unit is sending to steering  wheel 0xfe

VOLUME_UP:

RIGHT:

LEFT:

DOWN:

lights on PROBABLY: