PT Cruiser, 2001 - 2005

Intake Air Temperature (IAT) Sensor

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Description & Operation



The IAT sensor attaches to the intake air duct or is in the air tube. The IAT Sensor is a Negative Temperature Coefficient (NTC) Sensor that provides information to the PCM regarding the temperature of the air entering the intake manifold. The PCM sends 5 volts to the sensor and is grounded through the sensor return line. As temperature increases, resistance in the sensor decreases.

Battery Temperature

The intake air temperature sensor replaces the intake air temperature sensor and the battery temperature sensor. The PCM uses the information from the inlet air temperature sensor to determine values for the PCM to use as an intake air temperature sensor and a battery temperature sensor.

The battery temperature information along with data from monitored line voltage (B+), is used by the PCM to vary the battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures.

The battery temperature information is also used for OBD II diagnostics. Certain faults and OBD II monitors are either enabled or disabled depending upon the battery temperature sensor input (example: disable purge, enable LDP) Most OBD II monitors are disabled below 20F.

Intake Air Temperature (Iat) Sensor

The inlet air temperature sensor replaces the intake air temperature sensor and the battery temperature sensor. The PCM uses the information from the inlet air temperature sensor to determine values to use as an intake air temperature sensor and a battery temperature sensor. The Intake Air Temperature (IAT) sensor value is used by the PCM to determine air density. The PCM uses this information to calculate:



Injector pulse width
 
Adjustment of ignition timing (to prevent spark knock at high intake air temperatures)
 

Removal & Installation



  1. Remove the air cleaner lid; disconnect the inlet air temperature sensor and makeup air hose.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Disconnect electrical connector from the sensor
  6.  
  7. Remove the sensors.
  8.  

To install:

  1. Install sensor.
  2.  
  3. Attach electrical connector to sensor.
  4.  
  5. Connect the negative battery cable.
  6.  
  7. Install the air cleaner lid; connect the inlet air temperature sensor and makeup air hose.

    Click image to see an enlarged view

    Fig.

  8.  

 
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