Intake Air Temperature Sensor
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The Intake Air Temperature (IAT) sensor is a variable resistor, sometimes called a thermistor. The IAT sensor measures the temperature of the air entering the engine. The ECM supplies 5 volts to the IAT signal circuit. When IAT sensor is cold, sensor resistance is high. When air temperature increases, sensor resistance lowers. With high sensor resistance, ECM detects a high voltage on the IAT signal circuit. With lower sensor resistance, ECM detects a lower voltage on IAT signal circuit. If ECM detects an out of range voltage in the IAT signal circuit, a DTC will set. To diagnose, see SELF-DIAGNOSTICS - 6.6L SIERRA & SILVERADO - DIESEL article.