Liberty, Wrangler, 1997-2005

Intake Air Temperature Sensor

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Operation



The 2 wire Intake Manifold Air Temperature (IAT) sensor is installed in the intake manifold with the sensor element extending into the air stream.

The IAT sensor is a two-wire Negative Thermal Coefficient (NTC) sensor. Meaning, as intake manifold temperature increases, resistance (voltage) in the sensor decreases. As temperature decreases, resistance (voltage) in the sensor increases.

The IAT sensor provides an input voltage to the Powertrain Control Module (PCM) indicating the density of the air entering the intake manifold based upon intake manifold temperature. At key-on, a 5volt power circuit is supplied to the sensor from the PCM. The sensor is grounded at the PCM through a low-noise, sensor-return circuit.

The PCM uses this input to calculate the following:



Injector pulse-width
 
Adjustment of spark timing (to help prevent spark knock with high intake manifold air-charge temperatures)
 

The resistance values of the IAT sensor are the same as for the Engine Coolant Temperature (ECT) sensor.

Removal & Installation



3.7L Engine

The Intake Manifold Air Temperature (IAT) sensor is installed into the left side of intake manifold plenum.

  1. Disconnect electrical connector from IAT sensor. Clean dirt from intake manifold at sensor base.
  2.  
  3. Gently lift on small plastic release tab or and rotate sensor about 1/4 turn counterclockwise for Removal & Installation. Check condition of sensor O-ring.

    Click image to see an enlarged view

    Fig.

  4.  

To install:

The intake manifold air temperature (IAT) sensor is installed into the left side of intake manifold plenum.

  1. Check condition of sensor O-ring.
  2.  
  3. Clean the sensor mounting hole in the intake manifold.
  4.  
  5. Position the sensor into intake manifold and rotate clockwise until past release tab.
  6.  
  7. Install electrical connector.
  8.  

4.0L Engine

The Intake Manifold Air Temperature (IAT) sensor is installed into the intake manifold plenum near the front of the throttle body.

  1. Disconnect electrical connector from sensor.
  2.  
  3. Remove sensor from intake manifold.
  4.  

To install:

The Intake Manifold Air Temperature (IAT) sensor is installed into the intake manifold plenum near the front of the throttle body.

  1. Install sensor into intake manifold. Tighten sensor to 28 Nm (20 ft. lbs.) torque.
  2.  
  3. Connect electrical connector to sensor.
  4.  

 
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