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Scan Tester Diagnostic Circuit Check

The "Scan" Tester Diagnostic Circuit Check is an organized approach to identifying a problem created by a Computerized Engine Controls system. It must be the starting point for any driveability complaint diagnosis. The "scan data" may be used for comparison after completing the diagnostic circuit check and ensuring the self-diagnostic system is functioning properly.

Fig 1: Diagnostic Circuit Check Flow Chart
G94610Courtesy of GENERAL MOTORS CORP.