If the illumination turns on when you turn the lights on then the unit may be coded for an A6 which doesn't use speed over CAN. If the illumination doesn't turn on then you may have an issue with your CAN wires.
yes I get illumination and the map colours also change to night mode when you switch the lights on so I think can is good. Looks like it just probably needs coded to the car as the cd/radio etc all work ok too.
Will book it into the dealer and let you know how it goes.