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:

• Verify that the "Check Engine" or "Service Engine Soon" light is functional.
• Verify the ECM is operating and can recognize a fault.
• Verify scan data is available.
• Verify the engine can start.
• Determine if any codes are stored, and if so, retrieve them.