Test Description

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.

The numbers below refer to the step numbers on the diagnostic table.

2. Tests for proper ignition 3 voltage to the front axle actuator.
3. Tests for proper ground at the front axle actuator.
4. Tests for proper ground at the axle actuator control circuit through the transfer case switch.
5. Tests the transfer case switch ground circuit for an open.
6. Tests the transfer case switch for proper operation.

Fig 1: Four-Wheel Drive Does Not Engage (Steps 1-7)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Four-Wheel Drive Does Not Engage (Steps 8-13)

Courtesy of GENERAL MOTORS CORP.