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Home >> GMC >> 1993 >> Forward Control 6.2 J, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Controls - Theory & Operation >> Computerized Engine Controls (Gasoline) >> Electronic Control Module (ECM) >> Calibration Package (CALPAC)
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Calibration Package (CALPAC)

Some models use a PROM and a CALPAC. CALPAC provides fuel delivery back-up so engine runs in case of PROM or ECM failure. Any time ECM is replaced, PROM and CALPAC must both be installed into replacement ECM. If battery voltage is removed, CALPAC information is retained.

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