Diagnostic Starting Point - Data Link
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.
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.