Chrysler Neon 1995-1999 Repair Guide

Intake Air Temperature Sensor

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OPERATION



See Figures 1 and 2

The Intake Air Temperature (IAT) sensor measures the temperature of the intake air as it enters the engine. The sensor supplies one of the inputs the PCM uses to determine injector pulse width and spark advance. AS the intake air temperature varies, the IAT sensor's resistance changes resulting in a different input voltage to the PCM.

On 1995 vehicles, the IAT sensor threads into the intake manifold. On 1996-99 vehicles, the IAT and Manifold Absolute Pressure (MAP) sensors are combined into a single sensor which is attached to the intake manifold.



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Fig. Fig. 1: The IAT sensor and MAP sensor thread into the intake manifold on 1995 vehicles



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Fig. Fig. 2: Location of the IAT/MAP sensor-1996-99 SOHC engines



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Fig. Fig. 3: IAT/MAP sensor location-1996-99 DOHC engines

TESTING



See Figure 4

1995 Vehicles
  1. Visually check the connector, making sure it is attached properly and all of the terminals are straight, tight and free of corrosion.
  2.  
  3. With the ignition key OFF , detach the wire harness connector from the IAT sensor.
  4.  
  5. Connect a digital ohmmeter (DVOM) to the sensor terminals. The ohmmeter should read as follows:
    1. With the engine and sensor at normal operating temperature, about 200°F, the DVOM should read about 700-1,000 ohms.
    2.  
    3. With the engine and sensor at room temperature, about 70°F, the DVOM should read about 7,000-13,000 ohms.

      Click image to see an enlarged view

      Fig. Fig. 4: At room temperature, the IAT sensor resistance should be approximately 7,000-13,000 ohms

    4.  

  6.  

1996-99 Vehicles

See Figure 5

  1. Test the IAT/MAP sensor output voltage at the sensor connector, between terminals 1 and 4.
  2.  
  3. With the ignition ON , but the engine NOT running, the output voltage should be 4-5 volts. The voltage should drop to 1.5-2.1 volts with a hot, neutral idle speed condition. If OK, go to next step. If not OK, go to Step 4.
  4.  
  5. Test the PCM terminal 36 for the same voltage described in the previous step to check wire harness condition. Repair as necessary.
  6.  



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Fig. Fig. 5: IAT and MAP sensor terminal identification

  1. Test the MAP sensor ground circuit at the sensor connector terminal 1 and the PCM terminal 43. If OK, go to the next step. If not, repair as necessary.
  2.  
  3. Test the MAP sensor supply voltage between sensor connector terminal 3 and 1 with the ignition key ON . The voltage should be about 3.5-4.5 volts. There should also be 3.5-4.5 volts at terminal 61 of the PCM. If OK, replace the MAP sensor. If not, repair or replace the wire harness as required.
  4.  

REMOVAL & INSTALLATION



1995 Vehicles

See Figures 1, 6, 7 and 8

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the engine cover.
  4.  
  5. Detach the electrical connector from the sensor.
  6.  



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Fig. Fig. 6: Detach the IAT sensor electrical connector

  1. Remove the sensor from the intake manifold.
  2.  



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Fig. Fig. 7: Use a ratchet and extension with a deep socket to loosen ...



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Fig. Fig. 8: ... then remove the IAT sensor from the intake manifold

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

1996-99 Vehicles

SOHC ENGINES

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Detach the electrical connector from the MAP/IAT sensor.
  4.  
  5. Unfasten the sensor mounting screws, then remove the sensor from the vehicle.
  6.  

To install:
  1. Insert the sensor into the intake manifold, but make sure not to damage the O-ring seal.
  2.  
  3. Tighten the mounting screws to 20 inch lbs. (2 Nm) for vehicles with a plastic intake manifold. For vehicles with an aluminum intake manifold, tighten the sensor to 2 inch lbs. (3 Nm).
  4.  
  5. Attach the electrical connector to the sensor.
  6.  
  7. Connect the negative battery cable.
  8.  

DOHC ENGINES

See Figure 3

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air inlet duct wing nut and duct from the intake manifold.
  4.  
  5. Detach the electrical connector from the IAT/MAP sensor.
  6.  
  7. Unfasten the sensor mounting screws, then remove the sensor from the vehicle.
  8.  

To install:
  1. Insert the sensor into the intake manifold, but make sure not to damage the O-ring seal.
  2.  
  3. Tighten the mounting screws to 20 inch lbs. (2 Nm) for vehicles with a plastic intake manifold. For vehicles with an aluminum intake manifold, tighten the sensor to 2 inch lbs. (3 Nm).
  4.  
  5. Attach the sensor electrical connector.
  6.  
  7. Install the air inlet duct to the intake manifold and secure with the wing nut. Make sure the duct doesn't interfere with the spark plug wires.
  8.  
  9. Connect the negative battery cable.
  10.  

 
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