Circuit/System Description
The intake air temperature (IAT) sensor 1 is a variable resistor that measures the temperature of the air in the sensor bore. The engine control module (ECM) supplies 5 V to the IAT sensor 1 signal circuit and a ground for the IAT sensor 1 low reference circuit. The signal varies with inlet air temperature and is displayed by the scan tool as °C (°F).
The IAT sensor 2 produces a frequency signal based on the inlet air temperature very close to the humidity sensor within the sensor bore. The signal varies with inlet air temperature and is displayed by the scan tool as °C (°F) and Hertz (Hz). The ECM applies 5 V to the circuit. The signal circuit is shared by the IAT sensor 2 and the humidity sensor. Ignition voltage and ground circuits are also supplied to the multifunction intake air sensor's internal circuits for these sensors:
- IAT sensor 2
- Humidity sensor
- MAF sensor
The multifunction intake air sensor houses the following:
- IAT sensor 1
- IAT sensor 2
- Humidity sensor
- MAF sensor
- BARO pressure sensor
| IAT Sensor 1 | IAT Sensor 1 Resistance | IAT Sensor 1 Signal Voltage |
|---|---|---|
| Cold | High | High |
| Warm | Low | Low |
| IAT Sensor 2 | IAT Sensor 2 Frequency | IAT Sensor 2 Temperature |
|---|---|---|
| Cold | 45 Hz | -40°C (-40°F) |
| Warm | 302 Hz | 104°C (219°F) |