Firebird V6-3.8L VIN K (1995)
Ignition Control Module: Description and Operation
Ignition Control Module
PURPOSE
The ignition control module performs several functions:
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It powers the dual crankshaft position sensor internal circuits.
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It supplies the voltage signals that each respective Hall-effect switch pulses to ground to generate the 3X and 18X crankshaft position sensor
pulses.
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It determines the correct ignition coil firing sequence, based on how many 18X transitions occur during a 3X pulse. This coil sequencing
occurs at start-up. After the engine is running, the module remembers the sequence, and continues triggering the ignition coils in proper
sequence.
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It determines whether or not the crankshaft is rotating in the proper direction, and cuts off fuel delivery and spark to prevent backfiring if
reverse rotation is detected.
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It sends a "crankshaft reference" (fuel control) signal to the Powertrain Control Module (PCM). The PCM determines engine RPM from this
signal. it is also used by the PCM to determine crankshaft position for Ignition Control (IC) spark advance calculations. (The falling edge of
each fuel control signal pulse occurs 70° before TDC of any cylinder)
