the abs light comes on to warn the system is faulty. usually a wheel speed sensor or the wires leading to it. disconnect the sensor take a resistance reading from each corner as you turn the wheel you may find one is very different to the other three if it is replace it if not check continuity of the wiring from the sensor to the control unit. the control itself is nearly 100% reliable unless it gets wet. hope this helps
simon smith, November 2009
