ABS Main Relay: Description and Operation

The combination relay is by the control module. It has two relay circuits, both controlled by the control module. The combination relay supplies power to the hydraulic unit solenoid valves and controls the hydraulic pump. The relay also has two built-in diodes. One diode eliminates the power surges induced when the pump motor cuts out, the other switches the ABS warning indicator on if the combination relay is not on or the control module is disconnected.