You antilock brakes work by sensing the speed each wheel is turning and watching for one to change speed radically from the others. There is a sensor mounted behind the brake disc (usually mounted to the steering knuckle). There is a "tone ring" mounted on the hub to which the brake disc is mounted. It looks like a ring with a bunch of equally spaced cuts in it. Sometimes the ring will start to fill up with oil, grease and debris. The sensor can also become covered with debris. Either of these conditions can cause erratic readings of the wheel speed and turn on the light. Just the computer saying "hey, I can't understand what the sensor is trying to tell me". Cleaning the sensor and ring can solve this problem. I have not been following your other thread(s) so I'm not up to speed on other brake/suspension issues you are having, but they very well could be related. If you have a noise or other systom coming from one side, I would certainly look into it right away.
BobK