Anti-Lock Brake System: Operation: Modulator

Modulator unit adjusts hydraulic pressure applied to each caliper based upon signals received from ABS control unit. Modulator unit consists of ABS pump and motor, accumulator, pressure switch, 3 solenoid valve assembles and 4 piston/valve assemblies.

Piston/valve assemblies control brake fluid pressure to each caliper. Each solenoid valve set consists of an inlet and outlet valve. Individual modulator pistons are used for each rear wheel, but are connected to a single solenoid valve set used for both rear wheels. The modulator pistons for the rear brakes have proportioning control valves to prevent rear wheel lock-up if ABS system malfunctions.