Express, Savana, G1500, G2500, G3500, 1998-2005

Intake Air Temperature Sensor

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Operation



The Intake Air Temperature (IAT) sensor determines the air temperature entering the intake manifold. Resistance changes in response to the ambient air temperature. The sensor has a negative temperature coefficient. As the temperature of the sensor rises the resistance across the sensor decreases. This provides a signal to the PCM indicating the temperature of the incoming air charge. This sensor helps the PCM to determine spark timing and air/fuel ratio. Information from this sensor is added to the pressure sensor information to calculate the air mass being sent to the cylinders. The IAT receives a 5-volt reference signal and the signal return is based upon the change in the measured resistance due to temperature.

Removal & Installation



This procedure is for the intake manifold mounted IAT sensor on 6.6L engines. Refer to the MAF sensor removal and installation procedure for other IAT sensors.

  1. Remove the air intake pipe.
  2.  
  3. Unplug the harness connector from the IAT sensor.
  4.  
  5. Remove the sensor from the intake manifold.
  6.  
  7. Installation is the reverse of removal. Tighten the sensor to 18 ft. lbs. (25 Nm).

    Click image to see an enlarged view

    Fig. Intake manifold IAT sensor (2) and connector (1)-6.6L engines

  8.  

Testing



  1. Remove the IAT sensor.
  2.  
  3. Measure and record the resistance of the IAT sensor at various temperatures, then compare those measurements to the following. The change in resistance should occur smoothly. If there are any sudden changes, the sensor is faulty.
  4.  

Gasoline engines:



-4°F: 28680 ohms
 
14°F: 16180 ohms
 
32°F: 9420 ohms
 
50°F: 5670 ohms
 
68°F: 3520 ohms
 
86°F: 2238 ohms
 
104°F: 1459 ohms
 
122°F: 973 ohms
 
158°F: 467 ohms
 
194°F: 241 ohms
 
230°F: 132 ohms
 
266°F: 77 ohms
 

Diesel engines; MAF mounted:



-4°F: 14700 ohms
 
14°F: 8970 ohms
 
32°F: 5650 ohms
 
50°F: 3660 ohms
 
68°F: 2440 ohms
 
86°F: 1650 ohms
 
104°F: 1150 ohms
 
122°F: 810 ohms
 
158°F: 430 ohms
 
194°F: 240 ohms
 
212°F: 190 ohms
 

Diesel engines; manifold mounted:



-4°F: 38480 ohms
 
14°F: 23670 ohms
 
32°F: 15000 ohms
 
50°F: 9765 ohms
 
68°F: 6517 ohms
 
86°F: 4448 ohms
 
104°F: 3100 ohms
 
122°F: 2203 ohms
 
158°F: 1171 ohms
 
194°F: 662 ohms
 
212°F: 508 ohms
 
248°F: 310 ohms
 
284°F: 198 ohms
 

  1. If the sensor tests outside of these ranges, replace the sensor.
  2.  

 
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