|Just out of curiousity, how do you know that they (speed sensors) are showing the correct speed? Does this car have a VSS in the mission?
I would still like to understand what are the differences if any in abs sensors/pickups are between the A3 and your MK2: reason being if the pickups are different, or the sensor is a different type than the modulator will not function properly, of course it is only tuned for its orginal setup...
Also one other issue with modulator functions, they are also tuned pressure wise to the original setup too... So you may also want to compare caliper piston area and effective disk radius (you can compare over all diameter should be fine)... trying to use another's vehicles modulator is not always the easiest thing to do, especially if you want it to function good enough to use.
Also: when you removed the "multicontact", you basically took off the harness to the modulator?
After this your calipers didn't drag until you applied the brakes again?
I'm not up on my vw/audi AWD systems, are there sensors on the RR diff?
For some functions of (generic) VSA, EBD, TCS will use RR diff info.... normally when your brakes are dragging, its not an ABS issue, the only functions that apply brakes are the previous generic functions which I mentioned.
Sweet setup, I like pics, it always makes the thread more interesting.