Electronic Brake Control Module: Description and Operation

CONTROLLER ANTILOCK BRAKE (CAB)
The Antilock Brake Controller (CAB) is a microprocessor-based device that monitors wheel speeds and controls the antilock functions.

The primary functions of the CAB are:
- monitor wheel speeds
- detect wheel locking tendencies
- control fluid pressure modulations to the brakes during antilock stop operation
- control the ABS warning indicator
- monitor the system for proper operation
- provide communication to the DRB III while in diagnostic mode
- store diagnostic information in non-volatile memory

The CAB continuously monitors the wheel speed sensors. When a wheel locking tendency is detected, the CAB will command the appropriate HCU valve to modulate brake fluid pressure to that wheel. Brake pedal position is maintained during an antilock 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 the proper operation. If the CAB detects a system malfunction, it can disable the antilock system and activate the ABS warning indicator. If the antilock function is disabled, the system will revert to standard base brake system operation.

The CAB inputs include the following:
- three wheel speed sensors
- brake lamp switch
- ignition switch
- battery voltage
- diagnostic communication (PCI BUS)
- G-sensor (internal acceleration sensor)

The CAB outputs include the following:
- six valve/solenoid drivers
- pump/motor actuation
- ABS warning indicator actuation
- diagnostic communication (PCI BUS)