Steering Wheel Angle Sensor
The steering wheel angle sensor (2) is integrated with the SRS-contact reel (1), which in turn is installed on the Steering wheel module (SWM).
Inside the steering wheel angle sensor there is a code wheel that follows the steering wheel's movement. 16 optic digital sensors read off the code wheel. The signal is to generate a specific pattern. This information is sent to Steering Angle Sensor Module (SAS) which, based on these signals, calculates among others steering wheel angle and steering wheel angle rate.
From and including model year 2010 the optic sensors are replaced by two magnet-resistive sensor. Using the difference between these sensors, the Steering wheel angle sensor module (SAS) can decide the steering wheel's position.
In total the steering wheel angle sensor can measure a range of +/- 720 degrees but the steering wheel can be turned mechanically max. +/-540 degrees.
Due to the DSTC-systems' confidence in the information from the steering wheel angle sensor, it is very important that the contact reel is turned to its center position when it is installed as well as when the wheels point straight ahead.
The contact reel and steering wheel angle sensor are calibrated together to have an angle 0 degrees when delivered as spare part. In addition, only a genuine Volvo steering wheel may be used.