Grand Cherokee 4WD V8-5.2L VIN Y (1998)
Electronic Brake Control Module: Description and Operation
CONTROLLER ANTILOCK BRAKES
Controller Antilock Brakes (CAB)
The Controller Antilock Brake (CAB) is a microprocessor-based device that monitors wheel speeds and controls the antilock functions.
The CAB contains dual microprocessors. A logic block in each microprocessor receives identical sensor signals. These signals are processed and
compared simultaneously.
The CAB monitors wheel speed sensor inputs continuously while the vehicle is in motion. However, the CAB will not activate any ABS components
as long as sensor inputs and the acceleration switch indicate normal braking.
The CAB is mounted to the HCU and operates the ABS system separate from other vehicle electrical circuits. CAB voltage source is through the
ignition switch in the RUN position.
The primary functions of the CAB are:
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monitor wheel speeds
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detect wheel locking tendencies
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control fluid pressure modulation to the brakes during antilock stop operation
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monitor the system for proper operation
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provide communication to the DRB while in diagnostic mode
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store diagnostic information in non-volatile memory
The CAB continuously monitors the speed of each wheel. When a wheel locking tendency is detected, the CAB will command the appropriate valve to
modulate brake fluid pressure in its hydraulic unit. Brake pedal position is maintained during an anti lock stop by being a closed system with the use of
3 accumulators. The CAB continues to control pressure in individual hydraulic circuits until a wheel locking tendency is no longer present. The CAB
turns on the pump/motor during an antilock stop.
The antilock brake system is constantly monitored by the CAB for proper operation. The CAB contains a self check program that disables the antilock
system and illuminates the ABS warning light when a system fault is detected. If the antilock function is disabled, the system will revert to standard
base brake system operation.
The CAB inputs include the following:
