Electronic Brake Control Module: Description and Operation

The Controller Antilock Brake (CAB) is a microprocessor-based device that monitors wheel speeds and controls the antilock functions. The CAB contains two microprocessors that receive identical sensor signals and then independently process the information. The results are then compared to make sure that they agree. Otherwise, the CAB will turn off the antilock and turn on the Antilock Brake System (ABS) amber warning lamp.

The primary functions of the CAB are to:
- detect wheel locking tendencies
- control fluid pressure modulation to the brakes during antilock stop
- monitor the system for proper operation
- provide communication to the DRB 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 in its hydraulic unit. Brake pedal position is maintained during an antilock 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 antilock stop.

The antilock brake system is constantly monitored by the CAB for proper operation If the CAB detects a system malfunction, it can disable the antilock system and turn on the ABS warning lamp. If the antilock function is disabled, the system will revert to standard base brake system operation.

CAB Inputs Include The Following:
- ABS Warning Lamp
- Diagnostic Communication
- Four Wheel Speed Sensors
- Ignition Switch
- Fused B+
- Stop Lamp Switch
- Traction Control Switch


CAB Outputs Include The Following:
- ABS Warning Light Actuation
- Voltage
- Eight Valves
- Ten Valves With Traction Control
- Diagnostic Communication
- Body Controller Communication
- Traction Control Lamp Illumination