DeVille V8-4.9L VIN B (1995)
Ignition Control Module: Description and Operation
The Ignition Control Module (ICM) is a switching device located in the distributor. The ICM performs several functions:
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It monitors the "ON-OFF," pulses produced by the magnetic pickup assembly.
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It creates 4X reference signal (4X CRANK) sent to the Powertrain Control Module (PCM) for ignition control.
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It provides a means for the PCM to control spark advance (BYPASS and IGNITION CONTROL) called "Ignition Control Mode."
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It provides a limited means of controlling spark advance without PCM input called "Module Mode."
