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Home >> GMC >> 1990 >> Forward Control 3.9 L >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Testing >> Chart A-4, Injector Circuit Diagnosis >> All But 2.5L >> Circuit Description
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Circuit Description

This chart should only be used if diagnosis in CHART A-3 indicated an injector circuit problem. If both injector circuits fail to blink when tested, diagnose one injector circuit at a time.

NOTE: Numbers below refer to circled numbers on diagnostic chart.
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