Description of Vehicle Communication Information

Description of parameters (steering angle sensor)

Introduction / status

Introduction
The steering angle sensor is integrated with the contact roller for the SRS-system and is installed on the steering wheel lever module. The function of the sensor is to sense the driver's steering wheel movements. The steering angle sensor consists of a steel disc with two hole-patterned grooves illuminated by several installed pairs of light-emitting diodes and phototransistors. The disc is mounted so that it follows the steering column's movements and then the phototransistors can sense the disc's movement. One pair of light-emitting diodes (IY, IX) reads an index groove with a unique groove pattern. The other pair (A, B) reads a groove with a repeated pattern around the disc (dark, light, dark, light, etc. The grooves' resolution is 1.5 degrees. Since the steering wheel can be turned several revolutions an additional two groups of light-emitting diodes must be used (R1, R2, R3, R4) to read off which steering wheel revolution one is at (normal <3). During the movement the SAS control module (Steering Angle Sensor) processes all information about the steering wheel's absolute position. In connection with start of the vehicle one has to turn the steering wheel a small angle, approx. 5 degrees in any direction to enable the control module to determine the steering wheel's position. This means that the wheel's angle and direction can be determined in relation to the driving direction. The information is used in the DSTC-system (together with other information about the vehicle's driving situation) to decide if the vehicle is driven stable and safe or is in a skid situation.

Steering wheel angle
The value displays the steering wheel angle in degrees.
0° = Steering wheel in the straight forward position
1° to 720° = Angle of the steering wheel when turning to the left
-1° to -720° = Angle of the steering wheel when turning to the right

LED IY status
The value displays the status of LED IY.
ON = LED IY active
OFF = LED IY not active

LED IX status
The value displays the IX status.
ON = LED IX active
OFF = LED IX not active

LED A status
The value displays the A status.
ON = LED A active
OFF = LED A not active

LED B status
The value displays the B status.
ON = LED B active
OFF = LED B not active

LED R1 status
The value displays the R1 status.
ON = LED R1 active
OFF = LED R1 not active

LED R2 status
The value displays the R2 status.
ON = LED R2 active
OFF = LED R2 not active

LED R3 status
The value displays the R3 status.
ON = LED R3 active
OFF = LED R3 not active

LED R4 status
The value displays the R4 status.
ON = LED R4 active
OFF = LED R4 not active

Power supply, steering wheel angle sensor module (SAS)
The value indicates battery voltage at the steering wheel angle sensor module (SAS).
Measurement range: 5 to 15 V

Power supply, central electronic module (CEM)
The value indicates battery voltage at the Central electronic module (CEM).
Measurement range: 5 to 15 V

LED circuit 1 status
The value displays the status of LED circuit 1
ON = LED circuit 1 is active
OFF = LED circuit 1 is not activate

LED circuit 2 status
The value displays the status of LED circuit 1
ON = LED circuit 2 is active
OFF = LED circuit 2 is not activate

Signal voltage, signal A
The value indicates the signal voltage for signal A.
Measurement range: 0 to 16 V

Signal voltage, signal B
The value indicates the signal voltage for signal B.
Measurement range: 0 to 16 V

LED circuit 1 current
The value displays the current through LED circuit 1.
Measurement range: 0 to 50 mA

LED circuit 2 current
The value displays the current through LED circuit 2.
Measurement range: 0 to 50 mA