Relay Operation

The ABS system has 2 relays, solenoid valve relay and pump motor relay. Both relays are mounted on top of hydraulic modulator. Current is supplied to both relays from battery through fuse panel. The ECU supplies a ground for relays when vehicle is running. This supplies a voltage signal from solenoid valve relay to front-control solenoids and to rear-control solenoid. Based upon speed sensor signals, ECU controls solenoid operation by supplying a ground to energize individual solenoids.

Pump motor relay closes when ground is provided through control unit. Pressure relieved by solenoid valve operation is returned to master cylinder by return pump motor.