Test Description

WARNING: This page is about a different car, the 2002 GMC Sierra, 2002 GMC Cab & Chassis Sierra, 2002 Chevrolet Silverado, and 2002 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 Diagnosis (Steps 1-4)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Four-Wheel Drive Does Not Engage Diagnosis (Steps 5-13)

Courtesy of GENERAL MOTORS CORP.