Purpose & Usage
The Diagnostic Circuit Check is an organized approach to identifying a problem created by an electronic engine control malfunction. It MUST be the starting point for any driveability complaint diagnosis, because it direct the service technician to the "next logical step" in diagnosing the complaint.
The purpose of the Diagnostic Circuit Check is to:
- Make sure that the "Check Engine" or "Service Engine Soon" light is functional, and what to do if it isn't.
- Make sure the ECM is operating and can recognize a fault, and what to do if it doesn't.
- Make sure scan data is available, and what to do if it isn't.
- Make sure the engine can start, and what to do if it can't.
- To determine if any codes are stored, and if so, retrieve them.