Envoy, Rainer, Trailblazer 2006-2007

Electronic Control Module

Print

Operation



4.2L Engine

Refer to Powertrain Control Module (PCM).

5.3L And 6.0L Engines

The powertrain has electronic controls to reduce exhaust emissions while maintaining excellent driveability and fuel economy. The Engine Control Module (ECM) is the control center of this system. The ECM monitors numerous engine and vehicle functions. The ECM constantly monitors the information from various sensors and other inputs, and controls the systems that affect vehicle performance and emissions. The ECM also performs the diagnostic tests on various parts of the system. The ECM can recognize operational problems and alert the driver via the Malfunction Indicator Lamp (MIL). When the ECM detects a malfunction, the ECM 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 ECM.

Removal & Installation



4.2L Engine

Refer to Powertrain Control Module (PCM).

5.3L And 6.0L Engines

NOTE
It is necessary to record the remaining engine oil life. If the replacement module is not programed with the remaining engine oil life, the engine oil life will default to 100%. If the replacement module is not programmed with the remaining engine oil life, the engine oil will need to be changed at 5000 km (3,000 mi) 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. Disconnect the negative battery cable.
  4.  
  5. Disconnect the cooling fan electrical connector for additional clearance while removing the ECM.
  6.  
  7. Depress the ECM/Transmission Control Module (TCM) cover retainers.
  8.  
  9. Remove the ECM/TCM cover from the ECM/TCM bracket.
    WARNING
    Do not touch the connector pins or soldered components on the circuit board in order to prevent possible ElectroStatic Discharge (ESD) damage to the ECM.


    NOTE
    It is not necessary to disconnect the ECM electrical connectors in order to remove the ECM from the ECM/TCM bracket. Only disconnect the electrical connectors if servicing of component requires disconnecting of the electrical connectors.


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

  10.  
  11. Disconnect the ECM electrical connectors from the ECM.
  12.  
  13. Release the bracket ECM retainers.
  14.  
  15. Tilt the ECM away from the ECM/TCM bracket.
  16.  
  17. Remove the ECM from the ECM bracket.
  18.  
  19. Only when replacement of the ECM/TCM bracket is necessary, remove the TCM.
  20.  
  21. Remove the ECM/TCM bracket retaining bolts.
  22.  
  23. Remove the ECM/TCM bracket from the vehicle frame.

    Click image to see an enlarged view

    Fig. Transmission Control Module (TCM) (1), ECM/TCM bracket (2) and Engine Control Module (3)-5.3L and 6.0L engines

  24.  

To install:

  1. If the ECM/TCM bracket was previously removed, install the ECM/TCM bracket to the vehicle frame.
  2.  
  3. Install the ECM/TCM bracket retaining bolts.
  4.  
  5. Tighten the ECM/TCM bracket bolts to 89 inch lbs. (10 Nm).
  6.  
  7. If the TCM was previously removed from the ECM/TCM bracket, install the TCM.
  8.  
  9. Insert the ECM into the retaining slots of the ECM/TCM bracket.
  10.  
  11. Secure the ECM to the ECM/TCM mounting bracket ensuring the ECM retaining tabs are fully engaged.
  12.  
  13. Connect the ECM electrical connectors to the ECM if previously removed.
  14.  
  15. Install the ECM/TCM cover to the ECM/TCM bracket.
  16.  
  17. Ensure the ECM/TCM cover retainers are fully engaged with the ECM/TCM bracket.
  18.  
  19. Connect the cooling fan electrical connector.
  20.  
  21. Connect the negative battery cable.
  22.  
  23. If the ECM was replaced the replacement ECM must be programmed.
  24.  

Testing



4.2L Engine

Refer to Powertrain Control Module (PCM).

5.3L And 6.0L Engines
  1. Clear the DTCs using a scan tool.
  2.  
  3. Idle the engine at the normal operating temperature.
  4.  
  5. Monitor the misfire current counters with a scan tool.
  6.  
  7. If any of the misfire current counters are not incrementing, proceed to the next step. If the misfire current counters are incrementing, then perform the following:

    Turn OFF the ignition.
     
    Disconnect the injector which displays the highest number of misfire current counters
     
    Turn ON the ignition, with the engine OFF
     
    Probe the ignition 1 voltage circuit of the fuel injector with a test lamp that is connected to a good ground
     
    If the test lamp illuminates, go to step 9. If the test lamp does not illuminate, test the ignition 1 voltage circuit of the fuel injector for an open, high resistance or a short-to-ground.
     

  8.  
  9. Observe the Freeze Frame/Failure Records for this DTC.
  10.  
  11. Turn OFF the ignition for 30 seconds.
  12.  
  13. Start the engine and operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
  14.  
  15. If the DTC failed this ignition, then perform the following:

    Turn OFF the ignition.
     
    Disconnect the injector which displays the highest number of misfire current counters
     
    Turn ON the ignition, with the engine OFF
     
    Probe the ignition 1 voltage circuit of the fuel injector with a test lamp that is connected to a good ground
     
    If the test lamp illuminates, go to step 9. If the test lamp does not illuminate, test the ignition 1 voltage circuit of the fuel injector for an open, high resistance or a short-to-ground.
     

  16.  
  17. Connect the J-44603 Fuel Injector Test Lamp between the control circuit of the fuel injector and the ignition 1 voltage circuit of the fuel injector.
  18.  
  19. Start the engine, and if the test lamp flashes, test for an intermittent and a poor connection at the fuel injector. If the test lamp does not flash, proceed to the next step.
  20.  
  21. If the test lamp remains illuminated, test the fuel injector control circuit for a short-to-ground. If the test lamp does not remain illuminated, proceed to next step.
  22.  
  23. Test the fuel injector control circuit for a short-to-voltage, an open or high resistance. If neither of these conditions exist, test for an intermittent and for a poor connection at the Engine Control Module (ECM).
  24.  
  25. If there is neither an intermittent nor a poor connection at the ECM, replace the ECM.
  26.  
  27. Clear the DTCs with a scan tool.
  28.  
  29. Turn OFF the ignition for 30 seconds.
  30.  
  31. Start the engine.
  32.  
  33. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
  34.  
  35. Observe the Capture Info with a scan tool. Check to see if there are any DTCs that have not been diagnosed.
  36.  

 
label.common.footer.alt.autozoneLogo