Econoline E550 V8-7.3L DSL Turbo VIN F (2002)
Intake Air Temperature Sensor: Description and Operation
Intake Air Temperature Sensor
Intake Air Temperature (IAT) Sensor
The Intake Air Temperature (IAT) Sensors are thermistor devices in which resistance changes with temperature. The electrical resistance of a
thermistor decreases as the temperature increases, and increases as the temperature decreases. The varying resistance affects the voltage drop across
the sensor terminals and provides electrical signals to the PCM corresponding to temperature.
Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of
the passive sensor causes a variation in total current flow.
Voltage that is dropped across a fixed resistor in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal
to the reference voltage minus the voltage drop across the fixed resistor.
The IAT signal provides air temperature information to the PCM. The PCM uses the air temperature information to operate the Exhaust Back-Pressure
(EBP) system and to determine the cold idle setpoint. During long idle periods at cold ambient temperatures, the setpoint will increase engine rpm.
