Circuit/System Verification
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
It may be necessary to drive the vehicle slightly forward to engage 4LO on the transfer case.
Verify the scan tool displays Disabled when you select 4HI and Enabled when you select 4LO.