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 number(s) on the diagnostic table.

2) - Lack of communication may be due to a partial malfunction or a total malfunction of the class 2 serial data circuit. The specified procedure will determine the condition.
5) - The presence of DTCs which begin with "U" indicate some other system control module is not communicating.

Fig 1: Diagnostic System Check - Cellular Communication

Courtesy of GENERAL MOTORS CORP.