Circuit/System Description
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2011 GMC Yukon XL, 2011 GMC Yukon, 2011 Chevrolet Tahoe, 2011 Chevrolet Suburban, and 2011 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The transfer case shift control module (TCCM) controls the transfer case actuator lock solenoid. The transfer case actuator lock solenoid is released by being energized. This is accomplished by grounding the lock solenoid control circuit during range changes, and 4WD Auto mode. Locking action is applied when power or ground are taken away from the lock solenoid, preventing the transfer case encoder motor (TCEM) from moving. The system is capable of providing a 2WD HI, 4WD HI and 4WD LO lock-up without the need of additional vehicle power to hold the transfer case in these positions.