Tyler did some test on my A4 today:
Pin 'B8' at the PCM end.. key/on eng/off my DVM reads reads 8.6 volts to chassis ground, verified it's a clean 8.6V DC with my scope. With Key/on Eng/on in neutral it reads 10.6V Dc to chassis ground, again verified with scope, it had a very small insignificant .2V noise ripple.. With key/on/eng/on left wheel jacked up in gear at 10 MPH the line is a 10.2 V to ground square wave with frequency changing with speed (4K per mile pulse), put the DVM in AC mode between B8 and chassis ground and it reads 11.2V AC at 10 MPH. .. Are you sure the box between your PCM and speedometer that B8 (drk grn/wht wire) feeds is set up OK.
As far as VSS key/on eng/off A32 yellow wire reads 0.06 to chassis ground, verified with scope, ppl wire reads 10.6V DC to chassis ground, verified with scope.key/on eng/on in gear at 10MPH yellow reads +/- 15V AC (30v peek to peek), ppl wire reads +12v DC with a little ripple, verified with scope.
I'm Bob.. 1994 Z28, A4, Stall, CAI, Cam, RR's, 342 rear, LT's , CatBack, Tuned