Intrigue V6-3.8L VIN K (1998)
Engine Control Module: Description and Operation
Circuit Description
PCM
Powertrain Control Module (PCM)
The PCM is responsible for maintaining proper spark timing to ensure optimum driveability and emissions control. The PCM uses the ignition control
(IC) spark timing method to calculate spark advance and ignition dwell over a wide range of engine speeds and loads. The PCM calculates IC spark
timing based on input signals from the following components:
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24X Crankshaft Position Sensor Reference.
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Ignition Control Module (ICM).
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Engine Coolant Temperature (ECT) Sensor.
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Engine Knock Sensor(s).
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Intake Air Temperature (IAT) Sensor.
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Mass Air Flow (MAF) Sensor.
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Transaxle Range or Park Neutral Position (PNP) switches.
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Vehicle Speed Sensor (VSS) / Transaxle Output Speed Sensor (TOSS).
The ignition system uses many of the same ignition module-to-PCM circuits as did previous Delco engine management systems using distributor type
ignition. The following describes the PCM to ignition control module circuits:
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3X reference PCM input
The ignition control module (ICM) generates the 3X reference signal from the 18X crankshaft position sensor. To generate the 3X reference signal, the
ICM processes the 18X CKP signal through divide-by-6 circuit. The ICM then sends the 3X reference signal to the PCM. The PCM uses this signal to
calculate engine speed and crankshaft position at engine speed above 1280 RPM (+/- 150 RPM.
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18X reference PCM input
The 18X crankshaft position (CKP) sensor generates the 18X Reference signal. The PCM uses the signal to calculate engine speed and crankshaft
position at engine speeds below 1280 RPM +/- 150 RPM. The 18X reference signal provides better signal resolution within the calibrated RPM range.
This increases idle quality and low speed driveability.
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Camshaft Position PCM input
The PCM uses this signal to determine the position of the cylinder #1 piston during its power stroke. This signal is used by the PCM to calculate true
Sequential Fuel Injection (SFI) mode of operation. The PCM compares the number of CAM pulses to the number of 18X and 3X reference pulses. If the
number of 18X and 3X reference pulses occurring between CAM pulses is incorrect, or if no CAM pulses are received while the engine is running, the