DeVille V8-4.6L VIN Y (1998)
Powertrain Control Module: Description and Operation
General System Description
Accessing PCM
The PCM receives data from various information sensors, determines the required fuel and idle speed values and then controls the IAC valve, eight fuel
injectors, and spark advance to maintain the optimum performance and driveability under all driving conditions. For more information on the PCM, refer
to Powertrain Control Module Diagnosis.
The fuel pump relay allows the fuel pump to be energized by the PCM. When the ignition is first turned On, the PCM energizes the fuel pump relay for
two seconds. This allows the fuel pump to run for two seconds and build up fuel pressure for cranking. The PCM then waits for ignition reference pulses
from the Ignition Control Module (ICM). Once the PCM sees references pulses, the PCM energizes the relay to run the fuel pump.
A faulty fuel pump relay may cause long cranking times and should set a Diagnostic Trouble Code.
The PCM monitors input signals from the following components as part of its ignition control function to determine the required ignition timing:
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Ignition Control Module
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Engine Coolant Temperature (ECT) sensor
^
Manifold Absolute Pressure (MAP) sensor
^
Park/Neutral Switch
^
Throttle Position (TP) sensor
^
Vehicle Speed Sensor (VSS)
^
Knock sensor.
