Diagnostic Starting Point

Begin the system diagnosis by checking for DTCs. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. The diagnostic system check 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 circuit.
• The identification of any stored DTCs and their status.

The use of the diagnostic system check will identify the correct procedure for diagnosing the system and where the procedure is located. If no shift interlock system DTCs are present, attempt diagnosis by symptom. See SYMPTOM DIAGNOSIS  .