NOTE: The 4x2 service replacement module cannot be interchanged with the 4x4 module. The service replacement 4x4 module is interchangeable with the 4x2 module.

The anti-lock brake control module is mounted to the HCU.

It is an on-board diagnostic, non-repairable unit consisting of two microprocessors and the necessary circuitry for their operation. The anti-lock brake control module monitors system operation during normal driving as well as during anti-lock braking.

Anti-lock brake module operation is as follows:

Under normal driving conditions, the microprocessor produces short test pulses to the solenoid valves that check the electrical system without any mechanical reaction.
Impending wheel lock conditions trigger signals from the anti-lock brake control module that open and close the appropriate solenoid valves. This results in moderate pulsations in the brake pedal.
The anti-lock brake module used in 4x4 application includes a G-sensor. It detects vehicle movement during a brake lockup event that is transferred to other wheels through the powertrain.

During normal braking, the brake pedal feel is identical to a standard brake system.

Most faults that occur in the anti-lock brake system will be stored as a diagnostic trouble code (DTC) in the keep-alive memory of the anti-lock brake control module. The DTCs can be retrieved by following the onboard diagnostic procedures.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Anti-Lock Brake Control Module

Use the Manual With the Right Hardware

When to See a Mechanic