Anti-Lock Brake System: Operation: Modulator

The modulator consists of 4 modulator pistons and 3 solenoid valves. Individual pistons and solenoids are used for the front wheels. Individual modulator pistons are used for each rear wheel, but are connected to a single solenoid valve 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.