Diagnostic Starting Point - Data Link Communications
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. 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.