PT Cruiser 2006-2007

Powertrain Control Module

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Operation



The powertrain has electronic controls to reduce exhaust emissions while maintaining excellent drivability and fuel economy. The Powertrain Control Module (PCM)-used in this vehicle, is the control center of this system. The PCM monitors numerous engine and vehicle functions. The PCM constantly looks at the information from various sensors and other inputs, and controls the systems that affect vehicle performance and emissions. The PCM also performs the diagnostic tests on various parts of the system. The PCM can recognize operational problems and alert the driver via the Malfunction Indicator Lamp (MIL). When the PCM detects a malfunction, the PCM stores a Diagnostic Trouble Code (DTC). The problem area is identified by the particular DTC that is set. The control module supplies a buffered voltage to various sensors and switches. Review the components and wiring diagrams in order to determine which systems are controlled by the PCM. The following are some of the functions that the PCM controls:



The engine fueling
 
The Ignition Control (IC)
 
The Knock Sensor (KS) system
 
The Evaporative Emissions (EVAP) system
 
The Secondary Air Injection (AIR) system (if equipped)
 
The Exhaust Gas Recirculation (EGR) system
 
The automatic transaxle functions
 
The alternator
 
The A/C clutch control
 
The cooling fan control
 

Removal & Installation



The Powertrain Control Module (PCM) engine control strategy prevents reduced idle speeds until after the engine operates for 200 miles (320 km). If the PCM is replaced after 200 miles (320 km) of usage, update the mileage and Vehicle Identification Number (VIN) in the new PCM. Use the scan tool to change the mileage and VIN in the PCM. If this step is not done, a Diagnostic Trouble Code (DTC) may be set and SKIM must be done or car will not start if it is a SKIM equipped car. With a SKIM car, you must do a secret key transfer also. Refer to the appropriate Powertrain Diagnostic Manual and the scan tool.


WARNING
To avoid possible voltage spike damage to the PCM, the ignition key must be off, and the negative battery cable must be disconnected before unplugging the PCM connectors.


NOTE
Take note of any radio presets before disconnecting the negative battery cable.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the negative battery cable and isolate the cable from making a connection unintentionally.
    WARNING
    If the negative battery cable is not disconnected properly, there is the possibility of damaging the PCM by contacting the positive battery cable at the Power Distribution Center (PDC).

  4.  
  5. Remove plastic clips that hold the wiring harness to the support bracket.
  6.  
  7. Unlock and disconnect the electrical connectors (1) from the Powertrain Control Module (PCM).

    Click image to see an enlarged view

    Fig. Powertrain Control Module (PCM) location

  8.  
  9. Remove the clutch reservoir and relocate.

    Click image to see an enlarged view

    Fig. Remove the clutch reservoir and relocate

  10.  
  11. Remove the 4 mounting bolts from the PCM mounting bracket.
  12.  
  13. Remove PCM and mounting bracket.
  14.  
  15. Remove the 3 mounting bolts from the PCM bracket to PCM.

    Click image to see an enlarged view

    Fig. Remove the PCM and PCM mounting bracket

  16.  

To install:

  1. Install the PCM bracket and the 3 mounting bolts to the PCM. Tighten the bolts to 106 inch lbs. (12 Nm).
  2.  
  3. Tip the PCM and bracket assembly into the bracket.
  4.  
  5. Locate the PCM and bracket assembly on the tab (2).

    Click image to see an enlarged view

    Fig. Locate the PCM and bracket assembly on the tab

  6.  
  7. Install the 4 mounting bolts to the PCM mounting bracket and tighten to 97 inch lbs. (11 Nm).
  8.  
  9. Relocate and install the clutch reservoir.
    NOTE
    The electrical connectors for the PCM are COLOR Coded.

  10.  
  11. Connect and lock the electrical connectors to the PCM.
  12.  
  13. Install the plastic clips that hold the wiring harness to the support bracket.
  14.  
  15. Connect the negative battery cable.
  16.  
  17. Use the scan tool to reprogram the new PCM with the original Vehicle Identification Number (VIN) and the vehicle-s actual mileage. If this step is not done, a Diagnostic Trouble Code (DTC) may be set.
  18.  

Testing



The Powertrain Control Module (PCM), used in this vehicle, is programmed with test routines that test the operation of the various systems the PCM controls. Some tests monitor internal PCM functions. Many tests are run continuously. Other tests run only under specific conditions, referred to as conditions for running the DTC. When the vehicle is operating within the conditions for running a particular test, the PCM monitors certain parameters and determines if the values are within an expected range. The parameters and values considered outside the range of normal operation are listed as conditions for setting the DTC. When the conditions for setting the DTC occur, the PCM executes the action taken when the DTC Sets. Some DTC-s alert the driver via the Malfunction Indicator Lamp (MIL) or a message. Other DTC-s do not trigger a driver warning, but are stored in memory. The PCM also saves data and input parameters when most DTC-s are set. This data is stored in the freeze frame and/or failure records.

The DTC-s are categorized by type. The DTC type is determined by the MIL operation and the manner in which the fault data is stored when a particular DTC fails. In some cases there may be exceptions to this structure. Therefore, when diagnosing the system it is important to read the action taken when the DTC sets and the conditions for clearing the DTC.

Many intermittent open or shorted circuits come and go with harness and connector movement caused by vibration, engine torque, bumps, and rough pavement.

  1. Test the wiring harness and connectors by performing the following:

    Move the related PCM connectors and wiring while monitoring the appropriate scan tool data
     
    With the engine running, move the related connectors and wiring while monitoring engine operation
     
    If harness or connector movement affects the data displayed, the component and system operation, or the engine operation, inspect and repair the harness or connections as necessary
     

  2.  
  3. Test the electrical connections and/or wiring by performing the following:

    Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body, backed-out
     
    Inspect for improperly formed or damaged terminals. Test for incorrect terminal tension
     
    Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body
     
    Inspect for corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation with little visible evidence. Look for swollen and stiff sections of wire in the suspect circuits
     
    Inspect for wires that are broken inside the insulation
     

  4.  

 
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