Park Avenue V6-3.8L SC VIN 1 (2005)
Engine Control Module: Description and Operation
POWERTRAIN CONTROL MODULE (PCM) DESCRIPTION
The powertrain control module (PCM) interacts with many emission related components and systems, and monitors emission related components and
systems for deterioration. OBD II diagnostics monitor the system performance and a diagnostic trouble code (DTC) sets if the system performance
degrades.
The malfunction indicator lamp (MIL) operation and the DTC storage are dictated by the DTC type. A DTC is ranked as a Type A or Type B if the
DTC is emissions related. Type C is a non-emissions related DTC.
The PCM is in the engine compartment. The PCM is the control center of the engine controls system. The PCM controls the following components:
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The fuel injection system
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The ignition system
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The emission control systems
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The on-board diagnostics
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The A/C and fan systems
The PCM constantly monitors the information from various sensors and other inputs, and controls the systems that affect the vehicle performance and
the emissions. The PCM also performs diagnostic tests on various parts of the system. The PCM can recognize operational problems and alert the
driver via the MIL. When the PCM detects a malfunction, it stores a DTC. The condition is identified by the particular DTC that is set. This aids the
technician in making repairs.
PCM FUNCTION
The powertrain control module (PCM) can supply 5 volts or 12 volts to the various sensors or switches. This is done through pull-up resistors to the
regulated power supplies within the control module. In some cases, even an ordinary shop voltmeter will not give an accurate reading because the
resistance is too low. Therefore, a DMM with at least 10 megaohms input impedance is required in order to ensure accurate voltage readings.
The PCM controls the output circuits by controlling the ground or the power feed circuit through the transistors or a device called an output driver
module.
EEPROM
The electronically erasable programmable read only memory (EEPROM) is a permanent memory that is physically part of the control module. The
EEPROM contains program and calibration information that the powertrain control module (PCM) needs in order to control the powertrain operation.
Special equipment, as well as the correct program and calibration for the vehicle, are required in order to reprogram the control module.
DATA LINK CONNECTOR (DLC)
The data link connector (DLC) is a 16-pin connector that provides the technician a means of accessing communication data for aid in the diagnosis.
This connector allows the technician to use a scan tool in order to monitor the various parameters, and display the DTC information. The DLC is
located inside of the drivers compartment, underneath the dash.
MALFUNCTION INDICATOR LAMP (MIL) OPERATION
The malfunction indicator lamp (MIL) is located in the instrument panel cluster. The MIL will display as either SERVICE ENGINE SOON or one of
the following symbols when commanded ON:
The MIL indicates that an emissions related fault has occurred and vehicle service is required. The following is a list of the modes of operation for the
