Steering Angle Sensor: Description and Operation

STEERING WHEEL POSITION SENSOR:
The steering wheel position sensor inputs to the rear wheel steering control module consists of 3 digital input circuits. The analog signal is sent from the TBC to the rear wheel steering control module via class 2. The steering wheel position sensor supply voltage is between 4.9-5.1 volts. Phase A and phase B circuits are digital pulse signals whose output represents one degree of steering wheel rotation. When observing the phase A and phase B data parameters on the scan tool, the parameters will not have the same value at the same time. When the steering wheel is rotated, the phase A and phase B data parameters will be shown as high or low on the scan tool. The marker pulse is a digital pulse that is displayed as high on the scan tool for 20° only when the steering wheel angle is between -10 and +10°. The steering wheel position sensor analog signal voltage is at or near 2.5 volts with the wheels at center. Voltage increases/decreases for less than 1 full turn (+/- 225°) then plateaus for remainder of wheel travel.

REAR WHEEL STEERING POSITION SENSOR:
The rear wheel position sensor has 2 signal circuits: position 1 and position 2. Position 1 is a linear measurement of voltage per degree. The voltage range for position 1 is from 0.25 to 4.75 volts, and the angular measurement range is from -620° to + 620°. At 0.25 volts the steering wheel has been rotated -600° past center. At 4.75 volts the steering wheel has been rotated +600° past center. Position 2 circuit is a linear measurement of voltage per degree. The voltage for position 2 increases or decreases from 0.25 to 4.75 volts every 180°. When the steering wheel is 0° or at center, position 1 and position 2 output signals measure 2.5 volts respectively.