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Home >> GMC >> 1991 >> Value Van 7.4 N >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes - Transmission >> Self-Diagnostic System >> Clearing Trouble Codes
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Clearing Trouble Codes

Trouble codes should be cleared after repairs have been completed. Also, some diagnostic charts require that codes be cleared before using diagnostic chart. To clear codes, remove PCM/TCM memory battery voltage for 30 seconds.

If no hard fault codes are present (only intermittent codes exist), proceed to TESTS W/O CODES article in this section for intermittent diagnostic procedures.