Control Module, Anti-Lock Electronic

The anti-lock brake electronic control module is located in the engine compartment behind the driver's side head lamp on a bracket mounted on the surface of the plastic fender apron.

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

In addition, the anti-lock brake electronic control module provides a speed signal to the programmable speedometer/odometer module (PSOM). Refer to Section 13-01 for additional information about the PSOM.

Under normal driving conditions, the microprocessors produce short test pulses to check the electrical system without any mechanical reaction. The anti-lock brake electronic control module continuously monitors the speed of each wheel to determine if any wheel is beginning to lock. When a wheel locking tendency is detected, the anti-lock brake electronic control module signals the appropriate solenoid valve in the anti-lock hydraulic control unit (2C215) to open or close as well as the pump motor to turn on and recycle brake fluid back to the brake master cylinder (2140). This results in moderate pulsations of the brake pedal (2455) and pump noise which may be heard in the passenger compartment. During normal braking, the brake pedal feel will be identical to a standard brake system.

Most concerns which occur to the anti-lock brake system will be stored as a coded number in the Keep-Alive Memory (KAM) of the anti-lock brake electronic control module. This means that once a code is stored, it will be retained by the anti-lock brake electronic control module even with the key in the OFF position. The codes can be retrieved by following the on-board diagnostic procedures. Refer to Diagnosis and Testing in this section.