Diagnostic Starting Point - Data Link Communications
WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. 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.