Ford Aerostar 1986-1997 Repair Guide

General Information


The Rear Anti-Lock Brake System II (RABS II) continually monitors rear wheel speed with a sensor mounted on the rear axle housing while the brakes are applied. When the teeth on the speed sensor ring, mounted on the ring gear, pass the sensor pole piece, an AC voltage is induced in the sensor circuit with a frequency proportional to the average rear wheel speed. In the event of an impending lockup condition during braking, the Anti-Lock Electronic Control Unit modulates the hydraulic pressure to the rear brake drums. This inhibits rear wheel lockup.