Intake Air Temperature Sensor

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The Intake Air Temperature (IAT) sensor is a variable resistor. IAT sensor is located in fresh air intake tube. IAT sensor is combined with MAF sensor assembly. See Figure . The IAT sensor has a signal and a low reference circuit. The IAT sensor measures the temperature of the air entering the engine. The PCM supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. When IAT sensor is cold, the sensor resistance is high. When air temperature increases, the sensor resistance decreases. With high sensor resistance, PCM detects a high voltage on the IAT signal circuit. With lower sensor resistance, PCM detects a lower voltage on the IAT signal circuit. Failure in IAT sensor circuit should set a related DTC. To diagnose, see SELF-DIAGNOSTICS - 8.1L AVALANCHE, SIERRA, SILVERADO, SUBURBAN & YUKON XL article.