Circuit Description

Vehicle Stability Enhancement System (VSES) uses lateral accelerometer input when calculating desired yaw rate. Usable output voltage range for lateral accelerometer 0.25-4.75 volts. Scan tool will report zero lateral acceleration as 2.5 volts with no sensor bias present. Lateral accelerometer sensor bias compensates for sensor mounting alignment errors and electronic signal errors.

DTC sets when one of the following exists:

• A reference lateral acceleration from data of yaw rate sensor, wheel speed sensors, and steering angle sensor is used to test lateral accelerometer signal. If during stable driving conditions, lateral accelerometer signal becomes larger than 0.26 g, EBCM controller will disregard signal so that a false EBCM intervention is prevented. A malfunction is detected if this condition continues for more than two seconds.
• Under normal driving conditions, long time filtered driving direction is straight ahead. Long time filtered lateral accelerometer value is called offset. If offset value is higher than 0.23 g, a malfunction is detected. Malfunction time depends on driving distance, vehicle speed and the amount of malfunctioning lateral accelerometer signal.
• Lateral accelerometer signal is limited to an electrical stop of 1.8 g. If lateral accelerometer signal is greater than 1.5 g for more than 500 milliseconds, a malfunction is detected.
• At a standstill, range of lateral accelerometer signal is less than 0.7 g. If lateral accelerometer signal is greater than 0.7 g at standstill, a malfunction is detected.
• Lateral accelerometer signal cannot change rapidly under normal driving conditions. If lateral accelerometer signal is changing faster than 55 g per second, a malfunction is detected.