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Home >> Chevrolet >> 1997 >> Venture LS >> Repair and Diagnosis (Single Page) >> Engine Performance >> Theory and Operation >> Engine Control System - Theory & Operation >> Computerized Engine Controls >> Input Devices >> Intake Air Temperature (IAT) Sensor

Intake Air Temperature (IAT) Sensor

IAT sensor is a thermistor (temperature sensitive resistor) mounted in the intake manifold. Low intake air temperature produces high internal sensor resistance, while high temperature causes low internal sensor resistance. The PCM/VCM supplies and monitors a 5-volt signal to sensor through a pull-down resistor in PCM/VCM.

IAT sensor, also known as a manifold air temperature sensor, allows PCM/VCM to determine intake air temperature. PCM/VCM uses signal to delay EGR until intake air temperature reaches about 40°F (5°C). If intake air temperature becomes excessively high, PCM/VCM compensates by slightly retarding ignition timing. After a vehicle has cooled overnight, IAT and ECT sensor signals (resistance and temperature) should be close to same reading. Failure in IAT sensor circuit should set a related diagnostic trouble code.

CAUTION: Measure O2S voltage with a Digital Volt-Ohmmeter (minimum 10-megohm impedance) only. Current drain of a conventional voltmeter could damage sensor.
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