Visual/Physical Inspection

WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Inspect for aftermarket devices which could affect the operation of the Manual Selectable 4-Wheel Drive System. Refer to CHECKING AFTERMARKET ACCESSORIES .
Inspect the easily accessible, or the visible system components for obvious damage or conditions which could cause the symptom.
Ensure all mechanical components are operative before diagnosing the electrical portion of the system.
In order to determine whether the vehicle is in 2-wheel drive (2WD) or 4-wheels drive (4WD), lift the vehicle so that the wheels can spin freely. With the transfer case control lever in 2HI, turn the rear propshaft. If the front propshaft does not move with the rear, the vehicle is in 2HI. If the tires and the front propshaft moves, the transfer case is actually in 4WD.
Make sure that the 4WD fuse is not open. If open, locate and repair the source of the overload. Refer to TESTING FOR SHORT TO GROUND . Replace the fuse.