Dakota 4WD V6-3.9L VIN X (1997)
Electronic Brake Control Module: Description and Operation
With Four Wheel Antilock Brakes
GENERAL INFORMATION
The Controller Anti-Lock Brake (CAB) module is mounted on the top of the Hydraulic Control Unit (HCU). It operates the Anti-Lock Brake
System (ABS) and is separate from other vehicle electrical circuits. CAB voltage comes through the ignition switch in the RUN position. The
CAB contains dual microprocessors. A logic block in each microprocessor receives identical sensor signals. These signals are processed and
compared simultaneously.
OPERATION
The module is used to monitor wheel speeds and modulate (control) hydraulic pressure in each brake channel. The modulated hydraulic pressure is
used to prevent wheel lockup during braking. Brake switch input is monitored to determine whether or not to prepare for possible anti-lock
braking. Wheel speed sensors are monitored to determine when a wheel is beginning to lock up. The CAB will operate the valves in the HCU to
control braking pressure during anti-lock braking.
The CAB also receives input from the 4x4 indicator switch, mounted on the transfer case. This switch is closed to ground when the transfer case is
shifted to four wheel drive mode. While in four wheel drive, the front and rear axles will operate together. With this input, the CAB is able to
modify its operation to allow for this. Should a need for anti-lock operation occur while in four wheel drive, the CAB will extend the amount of
allowable dump cycles.
SELF-DIAGNOSTIC FEATURES
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 Diagnostic Readout Box (DRB) 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.
