'94 Grand Am Intermittent Abs Light

I have a '94 G.A. SE/2.3L-4/AT
Recently it started doing some funky s**t with the anti-lock brake warning light. It comes on after the system self-check, and the first application of the brake pedal, but not all the time. There doesn't seem to be any rhyme or reason that triggers it. Shutting the car off, and restarting usually resets the light, but not always. The brakes feel OK, and they haven't been worked on very recently....front pads/rotors have @ 20K on them, rr. shoes/drums & hardware have <10K.
The thing is: it had done this before, after changing the alternator, and not getting a battery cable tight. This took care of it last time, but not now, even after replacing both terminals.
I just changed the oil, and looked at the front wheel sensors. They're intact, at least, but I don't know what to do beside taking it to a mechanic for diagnosis. :nutkick:
Any ideas, serious suggestions, etc.???????

Before you take it in to a mechanic, check the sensor wires at the plug, pull gently on them to make sure they are firmly attached to the plugs. The front sensor wires on mine were bad and causing the same problem. If that's not the case, find a mechanic or parts store that can pull abs codes from the computer. That should tell you what the problem is.