Controller Anti-Lock Brake (Cab)
The Controller Anti-Lock Brake (CAB) is a microprocessor-based device that monitors wheel speeds and controls the anti-lock functions.
The primary functions of the CAB are to:
- monitor wheel speeds
- detect wheel locking tendencies
- detect wheel slip
- control fluid pressure modulation to the brakes during an anti-lock stop and traction control operation
- monitor the system for proper operation
- provide communication to the DRBIII(R) while in diagnostic mode
- 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 via the hydraulic control unit (HCU). Brake pedal position is maintained during an anti-lock stop by being a closed system with the use of 2 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 anti-lock stop.
The anti-lock brake system is constantly monitored by the CAB for proper operation. If the CAB detects a system malfunction, it can disable the anti-lock system and turn on the ABS warning indicator. If the anti-lock function is disabled, the system will revert to standard base brake system operation.
The CAB inputs include the following:
- diagnostic communication (PCI Bus)
- four wheel speed sensors
- ignition switch
- fused B+
- brake lamp switch
- traction control switch
The CAB outputs include the following:
- ABS warning indicator actuation (PCI BUS)
- Red brake warning indicator actuation (PCI BUS)
- pump/motor actuation
- 10 valve/solenoid drivers
- diagnostic communication (PCI BUS)
- TRAC lamp (PCI BUS)
- TRAC OFF lamp (PCI BUS)