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Home >> Oldsmobile >> 1989 >> Custom Cruiser >> Repair and Diagnosis >> Engine Performance >> Ignition System - HEI-Est >> Operation >> Est System >> Reference (RPM) Wire
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Reference (RPM) Wire

Alternating current signals from the pick-up coil are converted by the ignition module converter to digital signals for used by the ECM. This supplies RPM data and crankshaft position reference to the ECM. Since the signal on this wire is used as an injector trigger reference on fuel injected vehicles, if wire is open or grounded, engine will not run.