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Home >> GMC >> 2002 >> Jimmy 2D Utility, Part Time, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 1418 (Engine Control System - 4.2L (Introduction)) >> Description and Operation >> Electronic Ignition (EI) System Description >> Modes of Operation
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Modes of Operation

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During normal operation the PCM controls all ignition functions. If either the CKP or CMP sensor signal is lost, the engine will continue to run because the PCM will default to a limp home mode using the remaining sensor input. As mentioned above, each coil is internally protected against damage from excessive voltage. If one or more coils were to fail in this manner, a misfiring condition would result. Diagnostic trouble codes are available to accurately diagnose the ignition system with a scan tool.

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