Test Description

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, 2003 Chevrolet Blazer, and 2002 GMC Sonoma. 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 procedure.

4 - Lack of communication may be because of a partial malfunction of the class 2 serial data circuit or due to a total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular condition.
5 - The symptom list in Symptoms will determine the correct diagnostic procedure to use.
6 - The presence of DTCs which begin with "U" indicate some other module is not communicating. The specified procedure will collect all the available information before you perform tests.