H3 2006

Engine Coolant Temperature Sensor

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Location



3.5L & 3.7L Engines

Specific to:

Hummer H3 2006-2010

The Engine Coolant Temperature (ECT) sensor is located on the right rear side of the cylinder head.

Specific to:

Hummer H3 2006-2010

The Engine Coolant Temperature (ECT) sensor is located on the right rear side of the cylinder head.

5.3L Engine

Specific to:

Hummer H3 2006-2010

The Engine Coolant Temperature (ECT) sensor is located on the left front side of the left cylinder head.

Specific to:

Hummer H3 2006-2010

The Engine Coolant Temperature (ECT) sensor is located on the left front side of the left cylinder head.

Operation



Specific to:

Hummer H3 2006-2010

The Engine Coolant Temperature (ECT) Sensor is a Negative Temperature Coefficient (NTC) Thermistor that monitors the engine coolant temperature. The ECT Sensor operates within a 5 volt DC reference range, and provides a linear input signal to the Powertrain Control Module (PCM) that is based upon the measured engine coolant temperature. The PCM uses data from the ECT Sensor to calculate air-fuel mixture, ignition timing, and fuel injector pulse width. In some instances, the ECT signal is used to control the engine cooling fans and the operation of the air conditioning (A/C) system.

Removal & Installation



3.5L & 3.7L Engines

Specific to:

Hummer H3 2006-2010

  1. Partially drain the engine coolant below the level of the Engine Coolant Temperature (ECT) sensor.

    Click image to see an enlarged view

    Fig. Exploded view of the ECT location and connections

  2.  
  3. Disconnect the ECT sensor electrical connector from the following:
    NOTE
    Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.



    The engine wiring harness
     
    The camshaft cover
     

  4.  
  5. Using the J 45861 carefully remove the ECT sensor from the cylinder head.
  6.  

To install:


NOTE
Replacement components must be the correct part number for the application. Components requiring the use of the thread locking compound, lubricants, corrosion inhibitors, or sealants are identified in the service procedure. Some replacement components may come with these coatings already applied. Do not use these coatings on components unless specified. These coatings can affect the final torque, which may affect the operation of the component. Use the correct torque specification when installing components in order to avoid damage.

  1. If installing the original sensor or a new sensor without sealant, apply thread sealer GM P/N 12346004 (Canadian P/N 10953480) or equivalent.
  2.  
  3. Using the J 45861 carefully install the ECT sensor into the cylinder head. Tighten the sensor to 10 ft. lbs. (14 Nm).
  4.  
  5. Connect the ECT sensor electrical connector to the following:

    The engine wiring harness
     
    The camshaft cover
     

  6.  
  7. Fill the engine coolant.
  8.  

Specific to:

Hummer H3 2006-2010

  1. Partially drain the engine coolant below the level of the Engine Coolant Temperature (ECT) sensor.

    Click image to see an enlarged view

    Fig. Exploded view of the ECT location and connections

  2.  
  3. Disconnect the ECT sensor electrical connector from the following:
    NOTE
    Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.



    The engine wiring harness
     
    The camshaft cover
     

  4.  
  5. Using the J 45861 carefully remove the ECT sensor from the cylinder head.
  6.  

To install:


NOTE
Replacement components must be the correct part number for the application. Components requiring the use of the thread locking compound, lubricants, corrosion inhibitors, or sealants are identified in the service procedure. Some replacement components may come with these coatings already applied. Do not use these coatings on components unless specified. These coatings can affect the final torque, which may affect the operation of the component. Use the correct torque specification when installing components in order to avoid damage.

  1. If installing the original sensor or a new sensor without sealant, apply thread sealer GM P/N 12346004 (Canadian P/N 10953480) or equivalent.
  2.  
  3. Using the J 45861 carefully install the ECT sensor into the cylinder head. Tighten the sensor to 10 ft. lbs. (14 Nm).
  4.  
  5. Connect the ECT sensor electrical connector to the following:

    The engine wiring harness
     
    The camshaft cover
     

  6.  
  7. Fill the engine coolant.
  8.  

5.3L Engine

Specific to:

Hummer H3 2006-2010


NOTE
Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.

  1. Drain the cooling system below the level of the ECT sensor.
  2.  
  3. Disconnect the engine wiring harness electrical connector from the Engine Coolant Temperature (ECT) sensor.

    Click image to see an enlarged view

    Fig. Disconnect the engine wiring harness electrical connector (1) from the ECT sensor

  4.  
  5. Remove the ECT sensor.

    Click image to see an enlarged view

    Fig. Remove the ECT sensor (1)

  6.  

To install:


NOTE
Replacement components must be the correct part number for the application. Components requiring the use of the thread locking compound, lubricants, corrosion inhibitors, or sealants are identified in the service procedure. Some replacement components may come with these coatings already applied. Do not use these coatings on components unless specified. These coatings can affect the final torque, which may affect the operation of the component. Use the correct torque specification when installing components in order to avoid damage.


NOTE
Use care when handling the coolant sensor. Damage to the coolant sensor will affect the operation of the fuel control system.

  1. Coat the ECT sensor threads with sealer GM P/N 12346004 (Canadian P/N 10953480), or equivalent.
  2.  
  3. Install the ECT sensor. Tighten the sensor to 15 ft. lbs. (20 Nm).
  4.  
  5. Connect the engine wiring harness electrical connector to the ECT sensor.
  6.  
  7. Refill the cooling system as required.
  8.  

Testing



Specific to:

Hummer H3 2006-2010


NOTE
Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.

Connection & Wiring Diagnosis

Specific to:

Hummer H3 2006-2010

Refer to the Electrical Wiring Diagram for component and connector locations, connector views, and circuit-specific information.

Many intermittent open or short circuits may be caused by wiring harness and connector movement due to vibration, engine torque, bumps and rough pavement, etc.

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

    Move the related connectors and wiring while monitoring the appropriate scan tool data.
     
    Move the related connectors and wiring with the component commanded ON and OFF. Using a suitable the scan tool, observe the component operation.
     
    With the engine running, move the related connectors and wiring while monitoring component 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 connector terminal pins and/or wiring by performing the following tests:

    Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body.
     
    Inspect for improperly formed or damaged terminals and 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/or brittle sections of wire in the suspect circuits.
     
    Inspect for wires that are broken inside the insulation by gently pulling on suspect sections of wiring.
     

  4.  

ECT Circuit Testing

Specific to:

Hummer H3 2006-2010

Use a suitable scan tool, a Graphing Multi-Meter (GMM), or a Digital Volt-Ohm Meter (DVOM) in order to view the ECT data.

ECT Sensor logic is relative to the scale of resistance: when the coolant temperature is low, the voltage is increased. When the coolant temperature is high, the voltage is decreased.

Use a suitable pyrometer or thermometer, as well as visual observation to verify that the cooling system is operating properly. If a cooling system fault is evident, repair as required before continuing.

If a DVOM is being used, additional information may be acquired by taking measurements at the sensor connector as well as the PCM connector. If a significant voltage drop is measured (greater than 0.5 volts DC), check the wiring harness and connections for corrosion, poor pin connections, or damaged wires.

If all engine wiring and pin connections are confirmed, disconnect the ECT Sensor to verify the signal with a DVOM, and verify PCM communication before replacing the ECT Sensor.

Click image to see an enlarged view

Fig. ECT Sensor Range Chart

ECT Sensor Strategy

Specific to:

Hummer H3 2006-2010

The ECT Sensor provides a linear input signal to the Powertrain Control Module (PCM) for a number of engine control system calculations. The ECT signal is compared with Manifold Absolute Pressure (MAP), Mass Air Flow (MAF), Intake Air Temperature (IAT), and Fuel Trim (HO2S) in order to determine the correct air-fuel mixture for measured operating conditions. In some cases the ECT Sensor input is used in concert with the A/C Pressure (ACP) Sensor input in order to determine cooling fan and A/C system operation.

Related Diagnostic Trouble Codes

Specific to:

Hummer H3 2006-2010



Click image to see an enlarged view

Fig. Related Diagnostic Trouble Codes

 
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