Circuit Description

The 5 inputs to the electronic brake control module (EBCM) which are used solely for vehicle stability enhancement are the longitudinal accelerometer, lateral accelerometer, yaw rate sensor, master cylinder pressure sensor and the steering wheel position sensor. The EBCM must detect valid inputs from all 5 sources during the initialization period in order to enable the vehicle stability enhancement system (VSES). Initialization must occur during the first 3000 meters of vehicle travel or 1000 meters of straight vehicle travel. If initialization cannot be achieved during this time period, the VSES remains inactive and the stability system disabled message is displayed. The EBCM does not attempt to reinitialize until the next ignition cycle. One or more DTCs often set, shortly after an unsuccessful initialization attempt, indicating the root cause of the failure. If this occurs, the stability system disabled message is no longer displayed. The service stability system message is displayed instead.

During aggressive driving conditions which repeatedly activate the VSES or traction control system (TCS), one or more of the solenoid coils may become overheated. The stability system disabled message is displayed at this time and the EBCM disables all VSES and TCS brake pressure applications in an attempt to decrease the solenoid temperatures. Coil temperatures are estimated by the EBCM based on ambient temperature and monitored solenoid activation and may not coincide with actual solenoid temperatures. The stability system disabled message turns OFF and normal VSES/TCS activity resumes when the EBCM determines the solenoids have cooled sufficiently.