Despite my mechanic's best efforts thus far, the ABS light still comes back on, albeit on a less frequent than before basis. To date, this is what my mechanic has done:

1. Cleaned both front sensors;
2. He checked the charging system:
3. Replaced both front sensors, and cleaned the rear sensor.

His diagnostic equipment suggested that the front left sensor was bad, but it continues to come on with the new sensors. He believes that there must be a short in the system somewhere.

After he does a repair, I drive the car around for a few days to see what, if any, difference there is. As noted above, the ABS light does not come on as frequently as before. Also, when it comes on, it stays on until I stop and re-start the car, at which time it resets. It seems to come on at low speeds, such as city driving, and very rarely at highway speeds. Is there anyone out there who has experienced this type of ABS light behavior?

By the way, after charging me for one front sensor, my mechanic has basically told me he will continue to work on the car for free until this problem is solved. I have been working with him for well over a year, and know that he is not ripping me off.