could you check whether there is a 2 pin connector (black & brown) not plugged in under the drivers seat? it comes out of the main wiring loom from the floor, but i can't find a home for it.

I can see the connector that you are talking about. Probably the best way to locate it is to look at the front of the seat. There is a fairly obvious bunch of wires which are covered in a sort of webbing tape. This webbed cable is layed in a u shape. My connector is actually touching this cable as it straightens up at the rear of the u shape which is just forward of a light brown multi pin connector. If this is the one then your connector plugs into this in the direction of the transmission tunnel. FYI my car is also an 01 S8. Good luck

Ron