Caprice V8-265 4.3L VIN W MFI (1995)
Intake Air Temperature Sensor: Description and Operation
Engine Coolant Temperature (ECT) Sensor
The Intake Air Temperature (IAT) sensor is a thermistor (a resistor which changes value based on temperature). It is mounted in the air intake duct. Low
temperature produces a high resistance and high temperature causes low resistance.
The Powertrain Control Module (PCM) supplies a 5 volt signal to the sensor through a resistor in the PCM and measures the voltage. The voltage will
be high when the intake air is cold, and low when the intake manifold air is hot. By measuring the voltage, the PCM knows the intake air temperature. A
failure in the IAT sensor circuit should set either a DTC 23 or DTC 25.
