RAM 2500 Truck 2WD V8-5.7L VIN D (2004)
Electronic Brake Control Module: Description and Operation
Fig.1 Hydraulic Control Unit
CONTROLLER ANTILOCK BRAKE (CAB)
The Controller Antilock Brake (CAB) is mounted to the Hydraulic Control Unit (HCU) and operates the ABS system.
The CAB voltage source is through the ignition switch in the RUN position. The CAB contains a self check program that illuminates the ABS warning
light when a system fault is detected. Faults are stored in a diagnostic program memory and are accessible with the DRB III scan tool. ABS faults
remain in memory until cleared, or until after the vehicle is started approximately 50 times. Stored faults are not erased if the battery is disconnected.
NOTE: If the CAB is being replaced with a new CAB is must be reprogrammed with the use of a DRB III.
TRW EBC 125 CONTROLLER ANTILOCK BRAKE
The CAB includes a microprocessor and two solenoids that control the valves that control brake pressure during RWAL braking and circuits that:
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Monitor the brake switch input to tell whether or not to prepare for possible antilock braking
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Monitor the brake fluid level switch input to tell whether or not the state of the hydraulics has a problem
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Monitor the wheel speed sensor input to determine when a rear wheel is tending to lock up
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Operate the integral hydraulic control unit (HCU) during antilock braking based on comparing the speed sensor to information programmed in
memory
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Detect RWAL system related problems and take diagnostic action
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Able to execute self-tests and output control commands
TRW EBC 325 CONTROLLER ANTILOCK BRAKE
The CAB includes a microprocessor and six solenoids that control brake pressure during antilock braking. The CAB also has circuits that monitor the
following:
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Brake switch input is monitored to determine whether or not to prepare for possible ABS braking
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Monitor the brake fluid level switch input to tell whether or not the state of the hydraulics has a problem
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Wheel speed sensors are monitored to determine when a wheel is tending to lock up. The CAB will operate the valves in the HCU to control
braking pressure during ABS braking
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Detect ABS system related problems and take diagnostic action
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Able to execute self-tests and output control commands
