I have the same problem,
Ii own a 2005 VW Golf mk5 and the F930bt unit. I had no problem with the handbrake as i didn't install the wiring at all and it always appear to be ON so i can play video on the move. The problem is i get no speedpulse and no data from the vertical axle of the guroscope sensor. The only thing i know so far, looking at the wiring harness, is that the speed sensor cable (orange colour i think) coming out of the unit leads nowhere to the car. I haven't got the time so far to visit a pioneer dealer but after reading your post i assume that this is a common VW problem. Wha