Conditions for Setting the DTC

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Position A signal or position B signal circuit on the rear position sensor must be less than 0.075 volts.
Position A signal or position B signal circuit on the rear position sensor must be greater than 4.925 volts.
The 5 volt reference circuit is open or shorted to ground.
The position sensor ground circuit is open.