Diagnostic Aids

WARNING: This page is about a different car, the 2013 GMC Yukon XL, 2013 GMC Yukon, 2013 Chevrolet Tahoe, 2013 Chevrolet Suburban, and 2013 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

The incremental position sensor and the rotational position sensor both show position in degrees and should track each other. Monitor these sensors for erratic or unreasonable readings.
If the incremental position sensor is determined to be bad, the entire transfer case actuator will have to be replaced, as the incremental sensor is part of the actuator and cannot be replaced independently.
The transfer case fill and drain plugs are good sources for ground.