Begin the system diagnosis with the diagnostic system check. Refer to Diagnostic System Check - Vehicle . The Diagnostic System Check - Vehicle will provide the following information:
| • | The identification of the control modules which command the system | 
| • | The ability of the control modules to communicate through the serial data circuits | 
| • | The identification of any stored DTCs and their status | 
The use of the Diagnostic System Check - Vehicle will identify the correct procedure for diagnosing the system and where the procedure is located.