Dodge Durango

 Service Manual

Brakes » Rear wheel antilock brakes » Description and operation
Controller rear wheel antilock brakes

DESCRIPTION

The Controller Antilock Brakes (CAB) is a microprocessor which handles testing, monitoring and controlling the ABS brake system operation (Fig. 1). The CAB functions are:

• Perform self-test diagnostics.
• Monitor the RWAL brake system for proper operation.
• Control the RWAL valve solenoids.

NOTE: If the CAB needs to be replaced, the rear axle type and tire revolutions per mile must be programed into the new CAB. For axle type refer to Group 3 Differential and Driveline. For tire revolutions per mile refer to Group 22 Tire and Wheels. To program the CAB refer to the Chassis Diagnostic Manual.

Fig. 1 RWAL CAB

1 - RWALCAB

OPERATION

SYSTEM SELF-TEST

When the ignition switch is turned-on the microprocessor RAM and ROM are tested. If an error occurs during the test, a DTC will be set into the RAM memory. However it is possible the DTC will not be stored in memory if the error has occurred in the RAM module were the DTC's are stored. Also it is possible a DTC may not be stored if the error has occurred in the ROM which signals the RAM to store the DTC.

CAB INPUTS

The CAB continuously monitors the speed of the differential ring gear by monitoring signals generated by the rear wheel speed sensor. The CAB determines a wheel locking tendency when it recognizes the ring gear is decelerating too rapidly. The CAB monitors the following inputs to determine when a wheel locking tendency may exists:

• Rear Wheel Speed Sensor
• Brake Lamp Switch
• Brake Warning Lamp Switch
• Reset Switch
• 4WD Switch (If equipped)

CAB OUTPUTS

The CAB controls the following outputs for antilock braking and brake warning information:

• RWAL Valve
• ABS Warning Lamp
• Brake Warning Lamp

Rear wheel antilock

Controller rear wheel antilock brakes

Rwal valve

Rear wheel speed sensor and exciter ring

Brake warning lamps

Brake lamp switch