Ram 1500, 2500, 3500, 2WD and 4WD, 2001-2005

Intake Air Temperature Sensor

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Operation



The Intake Air Temperature (IAT) sensor determines the air temperature inside the intake manifold. Resistance changes in response to the ambient air temperature. The sensor resistance decreases as the air temperature increases. This provides a signal to the ECM indicating the temperature of the incoming air charge. This sensor helps the ECM to determine spark timing and air/fuel ratio. The IAT is threaded and screws into the intake manifold.


NOTE
Only Multi-port Fuel Injected (MFI) vehicles are equipped with an IAT sensor.

The Intake Air Temperature (IAT) sensor determines the air temperature inside the intake manifold. Resistance changes in response to the ambient air temperature. The sensor resistance decreases as the air temperature increases. This provides a signal to the ECM indicating the temperature of the incoming air charge. This sensor helps the ECM to determine spark timing and air/fuel ratio. The IAT is threaded and screws into the intake manifold.


NOTE
Only Multi-port Fuel Injected (MFI) vehicles are equipped with an IAT sensor.

Testing




WARNING
Testing the wiring harness with the ECM still connected can cause serious damage to the processor. ALWAYS disconnect the ECM before testing the wiring harness, unless instructed otherwise.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Unplug the electrical connector at the sensor.
  6.  
  7. Using an ohmmeter, measure the resistance across the two terminals of the sensor. The sensor resistance should be less than 1340 ohms with the engine at normal operating temperature. Replace the sensor if not within specifications.
  8.  
  9. To test the wiring harness, unplug the ECM; test the harness between the proper ECM connector terminal and the sensor connector. Also check the harness between the proper ECM connector terminal and the sensor connector. If resistance is more than 1 ohm, repair the wiring harness.
  10.  
  11. Install the engine cover.
  12.  
  13. Connect the negative battery cable.

    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.

  14.  


WARNING
Testing the wiring harness with the ECM still connected can cause serious damage to the processor. ALWAYS disconnect the ECM before testing the wiring harness, unless instructed otherwise.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Unplug the electrical connector at the sensor.
  6.  
  7. Using an ohmmeter, measure the resistance across the two terminals of the sensor. The sensor resistance should be less than 1340 ohms with the engine at normal operating temperature. Replace the sensor if not within specifications.
  8.  
  9. To test the wiring harness, unplug the ECM; test the harness between the proper ECM connector terminal and the sensor connector. Also check the harness between the proper ECM connector terminal and the sensor connector. If resistance is more than 1 ohm, repair the wiring harness.
  10.  
  11. Install the engine cover.
  12.  
  13. Connect the negative battery cable.

    Click image to see an enlarged view

    Fig.



    Click image to see an enlarged view

    Fig.

  14.  

 
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