Circuit/System Verification
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.
IMPORTANT:
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.