Diagnostic Starting Point

Begin the system diagnosis with the A Powertrain On-Board Diagnostic (OBD) System Check. The Powertrain OBD System Check will provide the following information:
^ The identification of the control modules that command the system.
^ The ability of the control modules to communicate through the serial data circuit
^ The identification of any stored Diagnostic Trouble Codes (DTCs), and DTC statuses.

The use of the Powertrain OBD System Check will identify the correct procedure, and the location of the procedure to properly diagnose the system. Initial Inspection and Diagnostic Overview