97' GTI - ABS malfunct & signal
 

Looking for help.... I have a '97 GTI 2.0 with 4-wheel disc ABS and have had the ABS light on for several months. No ABS doesn't bother me, but now I need ABS functioning for my car to pass a safety.
Quick background; back in October/November -07 my e-brakle cable ( right rear ) snapped and the internal spring wire locked onto something so that it was lightly braking while I was driving. It was enough to overheat my left rear brake and smoke/burn things up. I needed new rotors and brakes soon anyways, so I did a full brake job ( front and rear ) in November ( rotors and pads and ... new e-brake cables ). Sensor looked fine, however I suspected that the ABS sensor at that wheel was destroyed. I bought the sensor which comes with the harness and plugged it in ( it plugs in under rear seat )thinking that this might be the issue and the ABS light is still on.
1) Does the sensor have to be installed at the wheel and driven to calibrate with the system? If I swap it with the car off, how would it know that I swapped the sensor?
2) Any other common problems that I should be looking for? VW troublshooting costs for this just plain scare me.

Other; My left turn signal is flashing twice as fast as it should and no external/internal bulbs are burned out anywhere.... what do I check next? Looking for a flasher relay but can't seem to ID it. This is part of the safety too!

Thanks for any tips!!