Prizm L4-1800cc 1.8L DOHC (1993)
Intake Air Temperature Sensor: Description and Operation
The Intake Air Temperature (IAT) sensor is located in the side of air cleaner.
The IAT sensor is a thermistor (a resistor whose resistance changes as a function of temperature). The ECT is a two wire sensor with a referance voltage
and a ground provided by the PCM. Low air temperature produces a high resistance and high temperatures result in a low resistance.
The PCM supplies a five-volt signal to the sensor through a resistor in the PCM and measures the signal voltage. The voltage will be high when the air is
cold and low when the air is hot.
The IAT sensor provides air temperature information to the PCM for calculating air density. The PCM uses IAT, MAP and engine speed to calculate the
amount of air flowing into the engine.
A failure in the IAT sensor circuit should set a Diagnostic Trouble Code (DTC) 24.
