Avenger, Sebring Coupe, Stratus Coupe, 1999-2006

Intake Air Temperature Sensor

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Operation



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.

Click image to see an enlarged view

Fig.

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
 

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.

Click image to see an enlarged view

Fig.

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
 

The Intake Air Temperature (IAT) sensor is a negative coefficient sensor that provides information to the Powertrain Control Module (PCM) regarding the temperature of the air entering the intake manifold.

Battery Temperature

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 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.

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 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.

Testing



  1. Turn the ignition off. If possible, allow the vehicle to sit with the ignition off for more than 8 hours in an environment where the temperature is consistent and above 20°F (-7°C).
  2.  
  3. Test drive the vehicle. The vehicle must exceed 30 mph (48 km/h) during the test drive. Do not cycle the ignition off when the test drive is completed.
  4.  
  5. With a scan tool, select View DTC-s.
  6.  
  7. If a DTC is not active, perform the following:
  8.  
  9. Refer to any Technical Service Bulletins (TSBs) that may apply.
  10.  
  11. Review the scan tool Freeze Frame information. If possible, try to duplicate the conditions under which the DTC set.
  12.  
  13. With the engine running at normal operating temperature, monitor the scan tool parameters related to the DTC while wiggling the wire harness. Look for parameter values to change and/or a DTC to set. Turn the ignition off.
  14.  
  15. Visually inspect the related wire harness. Disconnect all the related harness connectors. Look for any chafed, pierced, pinched, partially broken wires and broken, bent, pushed out, or corroded terminals. Perform a voltage drop test on the related circuits between the suspected inoperative component and the PCM.
    CAUTION
    Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.

  16.  
  17. Inspect and clean all PCM, engine, and chassis grounds that are related to the most current DTC.
  18.  
  19. If numerous trouble codes were set, use a wire schematic and look for any common ground or supply circuits.
  20.  
  21. For any Relay DTC-s, actuate the Relay with the scan tool and wiggle the related wire harness to try to interrupt the actuation.
  22.  
  23. For intermittent Evaporative Emission trouble codes perform a visual and physical inspection of the related parts including hoses and the Fuel Filler cap.
  24.  
  25. Use the scan tool to perform a System Test if one applies to failing component. A co-pilot, data recorder, and/or lab scope should be used to help diagnose intermittent conditions.

    Click image to see an enlarged view

    Fig. Intake Air Temperature (IAT) sensor connector end view

  26.  

 
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