Hi smatsen. Welcome to the forum. I have a '95 sitting in the yard right now with the same problem, ... Except I know the answer, at least for my van.
One very important clue is to notice when the light turns on. If it turns on right after you start the engine, it is likely a sensor or other electrical-related issue. If the light turns on after driving for anywhere from, ... Oh, ... A tenth of a mile to a few miles, (but never while you're standing still), you likely have a cracked tone ring by one of the front wheels.
The tone rings are toothed rings that spin with the wheels. The sensors detect the gaps between the teeth. Water gets between the ring and cv joint that it is mounted to, freezes and expands. That, and rust, cause the ring to break. That gap is detected by the sensor as an additional tooth which tells the computer that wheel is turning faster than the other one. It will accept that, thinking you're going around a bend in the road, but after a mile or more, it knows that can't be true so it knows there's a problem.
When the warning light turns on, there will be a diagnostic fault code memorized in the ABS computer that will lead you to the wheel with the problem. If you don't have a scanner that can access and talk to that computer, you can still look at the tone rings. When you're doing this for the first time, it is easier to do by removing the wheel and rotating the brake rotor by hand to inspect the ring.
I proved to my students that I could weld cast iron. I repaired the ring on my van, but by that time the other one had also cracked so I still have the same problem. There is no place I've ever found where you can buy a new tone ring. Normally you have to replace the entire half shaft. Instead, I went on a shopping trip last year to a dozen salvage yards and removed a few of them from old half shafts. If you do that, you have to find one from a similar vehicle so it will fit and have the same number of teeth. The front rings have 47 teeth.
Sunday, May 30th, 2010 AT 2:24 AM