Axiom 2WD V6-3.5L (2002)
Engine Control Module: Description and Operation
Powertrain Control Module (PCM)
The powertrain control module (PCM) is located in the engine compartment.
The PCM controls the following:
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Fuel metering system.
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Transmission shifting (automatic transmission only).
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Ignition timing.
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On-board diagnostics for powertrain functions.
The PCM constantly observes the information from various sensors. The PCM controls the systems that affect vehicle performance. The PCM performs
the diagnostic function of the system. It can recognize operational problems, alert the driver through the MIL (Check Engine lamp), and store diagnostic
trouble codes (DTCs). DTCs identify the problem areas to aid the technician in making repairs.
EEPROM
General Description
The Electronically Erasable Programmable Read Only Memory (EEPROM) is a permanent memory that is physically soldered within the PCM. The
EEPROM contains program and calibration information that the PCM needs to control powertrain operation.
EEPROM Programming
1. Set-up - Ensure that the following conditions have been met:
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The battery is fully charged.
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The ignition is "ON."
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The Vehicle Interface Module cable connection at the DLC is secure.
2. Program the PCM using the latest software matching the vehicle. Refer to up-to-date Techline equipment user"s instructions.
3. If the PCM fails to program, proceed as follows:
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Ensure that all PCM connections are OK.
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Check the Techline equipment for the latest software version.
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Attempt to program the PCM. If the PCM still cannot be programmed properly, replace the PCM. The replacement PCM must be
programmed.
Functional Check
1. Perform the On-Board Diagnostic System Check.
2. Start the engine and run for one minute.
3. Scan for DTCs using the Tech 2.
PCM Function
The PCM supplies either 5 or 12 volts to power various sensors or switches.The power is supplied through resistances in the PCM which are so high in
value that a test light will not light when connected to the circuit.In some cases, even an ordinary shop voltmeter will not give an accurate reading
because its resistance is too low. Therefore, a digital voltmeter with at least 10 megohms input impedance is required to ensure accurate voltage
readings. Tool J 39200 meets this requirement.The PCM controls output circuits such as the injectors, fan relays, etc., by controlling the ground or the
power feed circuit through transistors or through either of the following two devices:
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Output Driver Module (ODM)
