Hi fitpl. Welcome to the forum. Since the ABS light has come on, there will be a diagnostic fault code stored in the computer. You'll need to find a mechanic with a scanner that can access that computer to read the code(s) that will indicate the circuit with the problem.
Start by looking at the connectors for the two front wheel speed sensors. Check for corrosion on the pins or signs of frayed wires. The light turning on indicates an electrical problem was detected such as a break in the circuit to a sensor, or the signal was lost from one wheel while the brake pedal was not applied. The system activating when it shouldn't points to a loss of signal from one wheel while there is NOT an electrical failure that disables the system. That type of failure could be caused by metal filings or rust buildup on the magnet on the end of a sensor.
Also check each tone ring, (toothed ring) for cracks. On some models, the tone rings are built into the wheel bearing assemblies and cause a real lot of trouble from play in the bearings. The only fix for those is to replace the entire wheel bearing assembly but you'll need the scanner to identify which sensor signal is dropping out.
Sunday, August 22nd, 2010 AT 12:23 PM