Silverado 2008

Intake Air Temperature (IAT) Sensor

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Location



Specific to:

Chevrolet Silverado 1500 2008

The Intake Air Temperature (IAT) Sensor is integrated with the MAF sensor, it is located on the air cleaner assembly.

Operation



Specific to:

Chevrolet Silverado 1500 2008

Resistance changes in response to the ambient air temperature. The sensor has a negative temperature coefficient. As the temperature of the sensor rises the resistance across the sensor decreases. This provides a signal to the PCM indicating the temperature of the incoming air charge. This sensor helps the PCM to determine spark timing and air/fuel ratio. Information from this sensor is added to the pressure sensor information to calculate the air mass being sent to the cylinders. The IAT receives a 5-volt reference signal and the signal return is based upon the change in the measured resistance due to temperature.

Removal & Installation



4.3L, 4.8L, 5.3L And 6.0L Engines
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the air intake tube from the air cleaner assembly.

    Click image to see an enlarged view

    Fig. Air cleaner outlet resonator assembly-4.3L engines



    Click image to see an enlarged view

    Fig. Air cleaner outlet resonator assembly-4.8L, 5.3L & 6.0L engines

  6.  
  7. Detach the electrical connector from the MAF sensor.
  8.  
  9. Loosen the sensor seal clamp.
  10.  
  11. Remove the sensor from its mounting.
    NOTE
    On the 4.8L, 5.3L, 6.0L engines, the embossed arrow located on the sensor indicated proper air flow direction.



    Click image to see an enlarged view

    Fig. IAT/MAF sensor electrical connector-4.3L engines



    Click image to see an enlarged view

    Fig. IAT/MAF sensor and related components-4.3L engines



    Click image to see an enlarged view

    Fig. IAT/MAF sensor and related components-4.8L, 5.3L & 6.0L engines

  12.  

To install:


NOTE
Be sure to use new fasteners, as required.

  1. Position the sensor on its mounting.
  2.  
  3. Continue the installation in the reverse order of the removal procedure.
  4.  

Testing



Specific to:

Chevrolet Silverado 1500 2008


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

Connection And Wiring Diagnosis

Specific to:

Chevrolet Silverado 1500 2008

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:

Chevrolet Silverado 1500 2008

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

Related Diagnostic Trouble Codes

Specific to:

Chevrolet Silverado 1500 2008



Click image to see an enlarged view

Fig. Related Diagnostic Trouble Codes

IAT Sensor Strategy

Specific to:

Chevrolet Silverado 1500 2008

The IAT Sensor provides a linear input signal (See Figure 1) 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.

 
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