LaCrosse 2006-2007

Electronic Control Module

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The Electronic Control Module (ECM) may also be referred to as the Engine Control Module (ECM).

Operation



The Engine Control Module (ECM) interacts with many emission related components and systems, and monitors the 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 ECM is in the engine compartment and is the control center of the engine controls system. The ECM controls the following components:



The fuel injection system
 
The ignition system
 
The emission control systems
 
The on-board diagnostics
 
The A/C and fan systems
 
The throttle actuation control (TAC) system
 

The ECM constantly monitors the information from various sensors and other inputs, and controls the systems that affect the vehicle performance and the emissions. The ECM also performs diagnostic tests on various parts of the system. The ECM can recognize operational problems and alert the driver via the MIL. When the ECM detects a malfunction, the ECM stores a DTC. The condition area is identified by the particular DTC that is set.

Removal & Installation



3.6L Engine

WARNING
Turn the ignition OFF when installing or removing the control module connectors and disconnecting or reconnecting the power to the control module (battery cable, Powertrain Control Module (PCM)/Engine Control Module (ECM)/Transaxle Control Module (TCM) pigtail, control module fuse, jumper cables, etc.) in order to prevent internal control module damage.


WARNING
Control module damage may result when the metal case contacts battery voltage. DO NOT contact the control module metal case with battery voltage when servicing a control module, using battery booster cables, or when charging the vehicle battery.


WARNING
In order to prevent any possible electrostatic discharge damage to the control module, do no touch the connector pins or the soldered components on the circuit board.


NOTE
Remove any debris from around the control module connector surfaces before servicing the control module. Inspect the control module connector gaskets when diagnosing or replacing the control module. Ensure that the gaskets are installed correctly. The gaskets prevent contaminant intrusion into the control module.


NOTE
The replacement control module must be programmed.


NOTE
It is necessary to record the remaining engine oil life. If the replacement module is not programmed with the remaining engine oil life, the engine oil life will default to 100 percent. If the replacement module is not programmed with the remaining engine oil life, the engine oil will need to be changed at 3,000 miles (5,000 km) from the last engine oil change.

  1. Using a scan tool, retrieve the percentage of remaining engine oil. Record the remaining engine oil life.
  2.  
  3. Turn the ignition OFF.
    NOTE
    Ensure that there is no main relay circuit voltage (ECM Fuse).

  4.  
  5. Use a DVOM in order to measure the main relay circuit voltage at the ECM fuse in the underhood fuse block.
  6.  
  7. Disconnect the battery negative cable.
  8.  
  9. Remove the ECM fuse in the underhood fuse block.
  10.  
  11. Remove the TCM/Instrument Panel Cluster (IPC) fuse in the underhood fuse block.
  12.  
  13. Remove the ECM/TCM fuse in the underhood fuse block.
  14.  
  15. Unlock the body side (outboard) ECM electrical connector:
    1. Depress the ECM electrical connector lever lock.
    2.  
    3. Simultaneously rotate the ECM connector clamp lever and depress the lock slide.
      WARNING
      In order to prevent any possible electrostatic discharge damage to the ECM, do not touch the connector pins.

    4.  

  16.  
  17. Remove the body side (outboard) ECM connector.
  18.  
  19. Unlock and remove the engine side (inboard) ECM connector.
  20.  
  21. Remove the ECM redundant ground wire and bolt from the ECM.
  22.  
  23. Remove the ECM bolts.
  24.  
  25. Remove the ECM.
  26.  
  27. If necessary, perform the following steps:
    1. Remove the ECM bracket bolts.
    2.  
    3. Remove the ECM bracket.

      Click image to see an enlarged view

      Fig. Engine Control Module (ECM) location-3.6L engine

    4.  

  28.  

To install:

  1. Install the ECM bracket, as necessary.
  2.  
  3. Install the ECM bracket bolts, as necessary. Tighten the ECM bracket bolts to 89 inch lbs. (10 Nm).
    WARNING
    In order to prevent any possible electrostatic discharge damage to the ECM, do not touch the connector pins.

  4.  
  5. Install the ECM.
  6.  
  7. Install the ECM bolts. Tighten the ECM bolts to 89 inch lbs. (10 Nm).
  8.  
  9. Install the ECM redundant ground and bolt to the ECM. Tighten the ECM redundant ground wire bolt to 44 inch lbs. (5 Nm).
  10.  
  11. Install the engine side (inboard) ECM connector.
  12.  
  13. Install the body side (outboard) ECM connector.
  14.  
  15. Install the ECM/TCM fuse in the underhood fuse block.
  16.  
  17. Install the TCM/IPC fuse in the underhood fuse block.
  18.  
  19. Install the ECM fuse in the underhood fuse block.
  20.  
  21. Connect the negative battery cable to the battery.
  22.  
  23. If a new ECM is being installed, the ECM must be programmed.
  24.  
  25. Turn the ignition OFF for at least 5 seconds after the programming event is complete.
  26.  

3.8L Engine

For removal and installation, refer to Powertrain Control Module (PCM).

Testing



  1. Perform a careful underhood inspection when performing any diagnostic procedure or diagnosing the cause of an emission test failure. This can often lead to repairing a condition without further steps. Use the following guidelines when performing an inspection:
    1. Inspect all of the vacuum hoses for correct routing, pinches, cuts, or disconnects
    2.  
    3. Inspect any hoses that are difficult to see
    4.  
    5. Inspect all of the wires in the engine compartment for the following conditions:

      Burned or chafed spots
       
      Pinched wires
       
      Contact with sharp edges
       
      Contact with hot exhaust manifolds
       

    6.  

  2.  

The Engine Control Module (ECM) is programmed with test routines that test the operation of the various systems the ECM controls. Some tests monitor internal ECM functions. Many tests are run continuously. Other tests run only under specific conditions, referred to as conditions for running the Diagnostic Trouble Code (DTC). When the vehicle is operating within the conditions for running a particular test, the ECM 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 ECM 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 ECM also saves data and input parameters when most DTC-s are set.

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 ECM 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
     
    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

    Click image to see an enlarged view

    Fig. Engine Control Module (ECM) connector end view (C1)-3.6L engine



    Click image to see an enlarged view

    Fig. Engine Control Module (ECM) connector end view (C2)-3.6L engine

     

  4.  

 
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