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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 >> Clearing Trouble Codes

Clearing Trouble Codes

CAUTION: When battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.
NOTE: To prevent PCM damage, ensure ignition switch is in OFF position when disconnecting or reconnecting power to PCM.

DTCs should be cleared after repairs have been completed. Also, some diagnostic procedures require DTCs to be cleared before performing diagnostic procedure.

To clear DTC(s), use scan tool. With ignition on and engine off, connect a scan tool to Data Link Connector (DLC) located behind left side of dash. See Figure. Refer to scan tool manufacturer's instructions.

If no hard fault codes are present (only intermittent codes exist), proceed to TESTS W/O CODES - 6.5L TURBO DIESEL article for intermittent diagnostic procedures.