ABS Main Relay: Description and Operation

The ABS main relay, located in the power distribution center (PDC), has two functions. First, when the relay is energized, it supplies power to the valve/solenoids in the valve block assembly and the pump/motor relay coil. Second, when the relay is de-energized, it supplies a ground to turn on the ANTI LOCK warning lamp. The main relay is controlled by the Controller, Anti-lock Brake (CAB). The CAB energizes the main relay when it receives an ignition input signal.

When the Anti-Lock Brake System (ABS) module grounds the ABS power relay on circuit B20, the relay switches to connect circuit B15 and circuit A20 from PDC fuse 10. Circuit F15 from fuse 13 in the fuse block splices to feed the coil side of the ABS power relay Circuit B20 connects to cavity 34 of the ABS control module.

Circuit B15 is double crimped at the ABS power relay. One branch of circuit B15 supplies power to the coil side of the ABS pump motor relay The other branch of circuit B15 splices to cavities 3 and 33 of the ABS control module and to the hydraulic control unit.