Thanks Sergei.
Its a 2 pin connector, but both wires appear to be earths? they both bolt on to airbag metal casing.
I may have to ask A8 parts if they know where those wires go in the car.

Audi wiring is so funny.
I played around today with a continuity meter and the D2 seat wiring loom to find out where the two airbag grounds go.
Well it turns out one goes nowhere :)
when they reach the black plug, only one continues on, and goes to the brown 10-pin plug under the seat. On the diagram that ground just goes to the chassis ground, so its a ground-to-ground.
So TT 3-pin airbag should be compatable as it also has 3 wires one of which is a ground. Next test will be does the D2 airbag controller like the TT airbag.

Here is a picture of the 2nd D2 airbag ground going nowhere. I have confirmed this on another seat thats still in one piece, same set up.

http://forum.a8parts.co.uk/attachmen...1&d=1380989860

It's just earthing of airbag's module properly, not via seat chassis. Have no idea as to why they did this in such a difficult way. Perhaps because several suppliers involved: airbag supplier + seats by Recaro.