Steering Angle Sensor

The steering angle sensor measures the steering wheel angle and the rate of change of the steering wheel angle. These measurements are received by the ABS module and broadcast on the high speed CAN bus for use by other systems.

The steering angle sensor is mounted on the steering column upper shroud mounting bracket, immediately behind the multifunction switches, and is secured by two screws. A fly lead connects the sensor to the passenger compartment wiring harness via a four pin multiplug.

The sensor is housed in a 'U' shaped plastic casing and contains two offset LED (light emitting diode) facing two detectors.

An encoder ring is mounted on the inner steering column shaft and intersects the LED's and detectors. The encoder ring contains 60 slots which break and restore the light beams between the LED's and the detectors as the steering wheel is rotated. The ABS module is able to determine the direction of rotation of the steering wheel by monitoring when the light beams change state. The LED's and detectors are mounted in such a way that only one beam will change state, either to broken or restored, at any one time.

The center (straight ahead) position of the steering wheel has to be learned by the ABS module every time the ignition is switched ON. The steering angle sensor is unable to determine the center position so inputs from the yaw rate and lateral acceleration sensor and wheel speed signals are also used by the ABS module to help it perform this process. If extreme weather conditions are present, for example ice causing extreme wheel spin or understeer/oversteer, the ABS module may not be able to determine the center position of the steering wheel. In this situation 'DSC NOT AVAILABLE' will be displayed in the instrument cluster message center and the amber warning indicator will illuminate.

'DSC NOT AVAILABLE' will also be displayed if the ABS module detects a steering angle sensor fault. The amber warning indicator will illuminate until the fault is rectified.