I would also pull the ABS pick-up sensor at the wheels and clean them with brake cleaner. The sensors are magnets and are probably completely covered in fine metallic dust. Might even be a good idea to pull the front rotors and really clean the ring gear, which is mounted to the back side of the rotor, the spaces between the teeth of the ring gear are probably chock full of metallic dust as well.

Pretty sure your car has one sensor at each front wheel and a single sensors at the rear differential. Mine is set up the way, yours may vary. I wouldn't start looking at the rear sensor until everything up front had been checked and cleaned.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.