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Home >> GMC >> 1998 >> Forward Control 6.5 F >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 6.5L Turbo Diesel >> Self-Diagnostic System >> Entering & Exiting Diagnostic Mode

Entering & Exiting Diagnostic Mode

To enter diagnostic mode, the use of a scan tool is required. With ignition on and engine off, connect scan tool to Data Link Connector (DLC) located under left side of dash. See Fig 1. The On-Board Diagnostic (OBD) system will enter into a diagnostic system check. In this mode, PCM will display DTCs on scan tool. Refer to scan tool manufacturer's instructions. To exit diagnostic mode, turn ignition off and remove scan tool from DLC.

Fig 1: Identifying DLC Terminals
G95D35181Courtesy of GENERAL MOTORS CORP.