The controlling element of the ABS system is a microprocessor based Electronic Brake Control Module (ECBM). Inputs to the system include four speed sensors, the brake switch, ignition switch and unswitched battery voltage. Outputs include three bi-directional motor controls, two lamp controls, two solenoid controls, and the system enable relay. A serial data line located in terminal "9" of the Data Link Connector (DLC), is provided for service diagnostic tools (scan tools) and the assembly plant.
In later model vehicles that are equipped with traction control, the control module may be referred to as the Electronic Brake and Traction Control Module (EBTCM).
The EBCM monitors the speed of each wheel and the electrical status of the hydraulic unit. The EBCM's primary functions are to detect wheel lockup, control the brake system while in anti-lock mode, and monitor the system for proper electrical operation. When one or more wheels approach lockup during a stop, the EBCM will command appropriate valve positions to modulate brake fluid pressure and provide optimum braking. It will continue to command pressure changes in the system until a locking tendency is no longer noted.
The EBCM is a separate computer used exclusively for control of the anti-lock brake system. The unit also controls the retention and display of the ABS trouble codes when in the diagnostic mode. As the EBCM monitors the system or performs a self-check, it can react to a fault by disabling all or part of the ABS system and illuminating the amber ANTILOCK warning light.
REMOVAL AND INSTALLATION
- Disconnect the negative battery cable.
- Remove the retainers, then remove the lower instrument panel sound insulator panel, under the steering column.
- The EBCM is secured with either hex head screws or retaining tabs. If secured with screws, unfasten the screws securing the EBCM to the dash panel. If equipped with pressure tabs, use the tabs to release the EBCM from its mounting bracket.
See Figures 1 and 2
- Unplug the EBCM electrical connectors, then remove the EBCM from the vehicle.
- Installation is the reverse of the removal procedure.