Conditions for Setting the DTC

WARNING: This page is about a different car, the 2009 GMC Yukon, 2009 Chevrolet Tahoe, 2009 Chevrolet Suburban, and 2009 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

The transfer case control module sees a PWM (RPS) voltage that does not constantly change but remains high 5 volts or above indicating a short to voltage. Or it may remain low indicating a short to ground 0.5 volts or less.
The module does not receive a 5-volt reference of 4.8-5.2 volts.
The RPS low reference circuits has an open or high resistance causing a low voltage situation.