Vehicle Stability Enhancement System

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The vehicle stability enhancement system adds an additional level of vehicle control to the electronic brake control module (EBCM)

Yaw rate is the rate of rotation about the vehicles vertical axis. The lateral accelerometer measures the sideways acceleration of the vehicle. The vehicle stability enhancement system is activated when the EBCM determines that the desired yaw rate and lateral forces do not match the actual altitude of the vehicle.

The desired altitude of the vehicle is calculated from the following inputs:

The position of the steering wheel
The speed of the vehicle
The lateral, or sideways acceleration of the vehicle
Yaw rate of the vehicle
Master cylinder brake pressure

The difference between the desired yaw rate and the actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM attempts to correct the vehicles yaw motion by applying differential braking to the appropriate wheel. The amount of differential braking applied to the left or right front wheel is based on both the yaw rate error and side slip rate error.

The vehicle stability enhancement system activations generally occur during aggressive driving, in turns, or on poor road conditions, without much use of the accelerator pedal. When braking during vehicle stability enhancement activation, the brake pedal pulsates at a higher frequency than the base braking system.