Chrysler Full-Size Vans 1989-1998 Repair Guide

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.

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

TESTING



See Figures 1, 2 and 3

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Unplug the electrical connector at the sensor.
  6.  
  7. Using a 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.  


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. 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.
  2.  
  3. Install the engine cover.
  4.  
  5. Connect the negative battery cable.
  6.  



Click image to see an enlarged view

Fig. Fig. 1: Using an ohmmeter, test the intake air temperature sensor for resistance across its two terminals



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Fig. Fig. 2: The IAT sensor circuit schematic



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Fig. Fig. 3: The IAT sensor's electrical connector terminal identification

REMOVAL & INSTALLATION



See Figures 4 and 5

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Unplug the electrical connector from the sensor.
  6.  
  7. Unscrew the sensor out of the intake manifold.
  8.  

To install:
  1. Install the sensor into the intake manifold and tighten it to 20 ft. lbs. (28 Nm).
  2.  
  3. Plug the connector into the sensor.
  4.  
  5. Install the engine cover.
  6.  
  7. Connect the negative battery cable.
  8.  



Click image to see an enlarged view

Fig. Fig. 4: Location of the IAT sensor-3.9L engine



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Fig. Fig. 5: Location of the IAT sensor-5.2L and 5.9L engines

 
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