Steering angle sensor

Arrangement in vehicle

The steering angle sensor is installed at the bottom end of the steering spindle in front of the steering flexible coupling.

Connector assignments:

Measuring range and matching

The sensor supplies a total steering angle signal with a resolution of approx. 0.7 ^o on the CAN bus.

A status variable is also sent on the CAN bus which provides information on the validity of the steering angle signal.

At the end of the assembly line or after replacing sensors, initialization must take place as part of DSC3 diagnosis with the diagnostic tester with the steering or the front wheels exactly in the straight-ahead position. During this procedure, the electrical offset of the sensor is calibrated and stored permanently in the sensor (EEPROM).

An identification number which is sent by the steering angle sensor along the CAN bus is additionally stored in the sensor and in the DSC3 control unit. If the IDs differ it will not be possible to enter the DSC3 system and steering angle initialization will be requested in DSC3 diagnosis.

This is intended to avoid introducing a faulty offset value when using a brand-new steering angle sensor or when installing a sensor which has already been used in another vehicle.

Measuring principle

In the same way as the EDC steering angle sensor, this sensor consists of two precision potentiometer wipers which are offset by 90 ^o and which supply signal voltages of 0 to approx. 4.5 V.

The processor logic (microcontroller with CAN module) additionally incorporated in the sensor calculates the current steering wheel rotation from the individual voltages and monitors the plausibility of the total steering angle (90 ^o monitoring).

The sensor logic looses the current steering wheel rotation value if the voltage supply is interrupted (e.g. as the result of disconnecting the battery). In this special case, the current steering wheel rotation is re-calculated by statistical evaluation of the front wheel speeds (sent via CAN).