Electronic Stability Control
Electronic stability control utilizes onboard computers to monitor vehicle direction and stability. If the vehicle is not going in the direction the driver is steering, the system uses individual wheel brakes to maintain control.
Using input sensors the control module continuously monitors vehicle steering and direction. These sensors include the four wheel speed sensors mentioned earlier, the vehicle speed sensor, and a few other directional and speed inputs. It estimates the direction of the skid and applies different brake units in order to counter and regain stability and control. It uses several other input sensors including the:
Steering Wheel Position Sensor: The steering wheel position sensor is used to inform the control module of the drivers intended direction. It takes this information and compares it to the vehicle's actual direction in order to make an informed braking decision. These decisions are based on factory set parameters. The sensor is located on the steering shaft and looks like a small clock spring.
Yaw Rate Sensor: This sensor is located somewhere in the passenger's compartment under the center console or front seat. It too is used to sense vehicle direction. Its purpose is to sense when a vehicle is beginning to fishtail and spin sideways.
Lateral Acceleration Sensor: This is known as the G-sensor and is capable of sensing the speed and force the vehicle has while entering a turn. Note that the Yaw Rate and Steering Wheel Position sensors are sometimes combined together into a single unit.