RAM 2500 Van V8-318 5.2L VIN T Magnum CNG SFI (1997)
ABS Main Relay: Description and Operation
OPERATION
The Antilock Brake System (ABS) power relay is located in the engine compartment near the washer fluid reservoir. The relay supplies voltage to
the Hydraulic Control Unit (HCU) pump motor, front antilock valve solenoids and rear antilock valve solenoids. The relay also provides an input
signal to the Controller Antilock Brake (CAB). This signal tells the CAB that voltage has been supplied to the HCU pump motor.
CIRCUIT OPERATION
When the Controller Anti-Lock Brakes (CAB) grounds the ABS power relay on circuit B116, the relay contacts close and connect circuit A10
from fuse 7 in the Power Distribution Center (PDC) and circuit B120. Circuit A20 from fuse 5 in the fuse block splices to feed the coil side of the
ABS power relay
From the ABS power relay, circuit B120 splices to power the pump motor and all the solenoids in the front hydraulic valve. Circuit B120 also
supplies power to the solenoids in the rear hydraulic valve. Additionally, circuit B120 provides an input to cavity 34 of the CAB. The input tells
the CAB that power has been supplied to the pump motor.
