Diagnostic Starting Point-Data Link Communications
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.
Begin the diagnosis of the Data Link Communications by performing the Diagnostic System Check for the system in which the customer concern is apparent.
The Diagnostic System Check will direct you to the correct procedure within the Data Link Communications section when a communication malfunction is present.