What and where ia a "Steer Angle Sensor"?

There’s an old thread on here about “steering wheel alignment” that may have the answer you’re looking for.

 

Truck make & model? Paccar?

Since you have a voltage fault logged. Inspect connector at the sensor for secure. Suspect wiring issue or open sensor. Sometimes tilt column can dislodge connector from sensor from zip ties to tight. Also rotating column without steering shaft connected will break sensor internally.

Sensor is located below steering wheel. Remove column covers front and rear to access connector.

 

My little pickup has that switch on the dash
Manual says to switch on when roads are slippery .
Some kind of traction control ?

 

The steering angle calibration is as simple as centering the steering wheel, turning on the ignition switch, then turning lock-to-lock starting left then right and returning to center. ???

 

Thats one of them new fangled do dads built in todays autos to prepare them to drive themselves.

 

Steering angle is used for ABS and stability control. The ECU watches the sensor for steering action from Zero( straight ahead) as it relates to degree of turn from Right (positive) and Left(negative). When the wheel is turned weight is transfered to the opposing wheels. This matters because the ABS now knows that the wheels with less weight on them will likely lock up first during a braking event.

The only way I am aware to calibrate the sensor is using the corresponding diagnostic tool to 0 the sensor at wheels straight ahead, be it Bendix or Wabco systems. This should be done any time the sensor is replaced or the steering components are disconnected to ensure its accuracy.