Conditions for Setting the DTC

WARNING: This page is about a different car, the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

The transfer case shift control module tries to unapply, turn OFF the lock solenoid by grounding the motor control circuit.
If the module does not sense the battery voltage at the motor lock control circuit prior to applying the motor lock, the DTC sets.
Transfer Case Lock control reads back as a high voltage when a low voltage is expected.