Fig. 22: Identifying Intake Air Temperature Sensors
Courtesy of FORD MOTOR CO.
Voltage that is dropped across a fixed resistor in a series with sensor resistor determines voltage signal at PCM.
This voltage signal is equal to reference voltage minus voltage drop across fixed resistor. IAT provides air
temperature information to PCM. PCM uses air temperature information as a correction factor in calculation of
fuel, spark and MAF. IAT sensor provides a quicker temperature change response time than ECT or CHT
sensor.
Supercharged vehicles use 2 IAT sensors. Both sensors are thermistors. However, one is located before the
supercharger at air cleaner for standard OBD-II cold weather input, while the second sensor (IAT2) is located
after the supercharger in intake manifold. IAT2 sensor located after supercharger provides air temperature
information to PCM to control border-line spark and to help determine intercooler (charge air cooler) efficiency.
Currently 2 types of IAT2 sensors are used on supercharged vehicles. A screw in type and an integrated type,
which is part of Thermal Manifold Absolute Pressure (TMAP) sensor. See Fig. 22 and Fig. 24 . TMAP sensor
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline