You should start a new question, and please be sure to list the engine size and mileage. This post is nine years old and was a private conversation between just the two people. None of the other experts will see your addition or have the chance to reply. That does you a disservice.
You need to use a regular scanner to read fault codes in the Anti-lock Brake Computer. If a common, inexpensive code reader is used, those can only read codes in the Engine Computer. Also check the fuses. There are going to be two for this system. When one blows, the second circuit is needed to run the warning lights.
By far the most common problem with the ABS on GM front-wheel-drive cars is the front wheel bearings. Due to the design of the wheel speed sensors, they develop real wimpy signals to begin with. At around 15,000 miles, a little normal play develops in the bearings, and that lets the tone ring move away from the sensor, so the sensor develops an even weaker signal. Eventually it gets so weak that the computer can't read it. This is a mechanical problem that is solved by replacing the bearing. It comes with the speed sensor attached. The clue this is not an electrical problem is that would be detected as soon as you turned on the ignition switch, and that's when the warning light would turn on. When the bearing is causing the problem, the light will turn on for its six-second self-test sequence, then turn off. It won't turn on again until the car is moving, often as much as a few hundred feet or more.
If your light does stay on right away, you're going to need the diagnostic fault code to know where to start the diagnosis.
Thursday, March 9th, 2017 AT 11:53 AM