H3 2006

Intake Air Temperature Sensor

Print

Location



Specific to:

Hummer H3 2006-2010

The Intake Air Temperature (IAT) sensor is an integral part of the Mass Air Flow (MAF) sensor/Intake Air Temperature (IAT) sensor assembly which is mounted on the air intake duct. Refer to the Mass Air Flow (MAF) section for information regarding servicing this component.

Operation



Specific to:

Hummer H3 2006-2010

The Intake Air Temperature (IAT) Sensor is a Negative Temperature Coefficient (NTC) Thermistor that monitors the intake air temperature. The IAT 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 intake air temperature. The PCM uses data from the IAT Sensor to calculate air-fuel mixture, ignition timing, and fuel injector pulse width. The IAT Sensor is sometimes integrated with the Mass Air Flow (MAF) Sensor as a physical component.

Removal & Installation



Specific to:

Hummer H3 2006-2010

The Intake Air Temperature (IAT) sensor is an integral part of the Mass Air Flow (MAF) sensor/Intake Air Temperature (IAT) sensor assembly which is mounted on the air intake duct. Refer to the Mass Air Flow (MAF) section for information regarding servicing this component.

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.  

IAT 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 IAT data.

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

Inspect the air intake tube, the engine air filter, and the MAF and/or IAT sensors for contamination and physical damage in order to verify that the air induction system is in proper working order. If an air induction 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 IAT Sensor to verify the signal with a DVOM, and verify PCM communication before replacing the IAT Sensor.

Click image to see an enlarged view

Fig. IAT Sensor Range Chart

IAT Sensor Strategy

Specific to:

Hummer H3 2006-2010

The IAT Sensor provides a linear input signal to the Powertrain Control Module (PCM) for a number of engine control system calculations. The IAT signal is compared with Manifold Absolute Pressure (MAP), Mass Air Flow (MAF), Engine Coolant Temperature (ECT), and Fuel Trim (HO2S) in order to determine the correct air-fuel mixture for measured operating conditions.

Related Diagnostic Trouble Codes

Specific to:

Hummer H3 2006-2010



Click image to see an enlarged view

Fig. Related Diagnostic Trouble Codes

 
label.common.footer.alt.autozoneLogo