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Home >> GMC >> 1985 >> Forward Control 5.7 M, Automatic, 400/M40 >> Repair and Diagnosis >> Engine Performance >> Ignition System >> Ignition System - HEI-Est (CALIF) >> Testing >> Ignition Coil Resistance Check >> Secondary Resistance
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Secondary Resistance

With ohmmeter set in high range, connect leads to "TACH" terminal and to secondary terminal. Reading should be less than infinite (approximately 6,000 to 30,000 ohms). If reading is infinity, replace coil.