Circuit/System Description
The sensors listed below are integrated within the multifunction intake air sensor:
- IAT sensor 1
- IAT sensor 2
- Humidity sensor
- MAF sensor
- BARO pressure sensor
The intake air temperature (IAT) sensor 1 is a variable resistor that changes the voltage on the engine control module (ECM) supplied 5 V signal circuit. The signal varies with inlet air temperature in the sensor bore and is displayed by the scan tool as °C (°F). The IAT sensor 2 and the humidity sensor share the same circuit. The IAT sensor 2 signal is displayed by the scan tool as Hz (Hertz) and °C (°F).
The IAT sensor 1 produces an analog signal on pin-8 of the sensor. The IAT sensor 2 produces a frequency modulated signal on pin-1 of the sensor.
The sensors listed below share an ECM supplied 5 V reference circuit:
- IAT sensor 2
- Humidity sensor
- Barometric pressure (BARO) sensor
The sensors listed below share an ECM supplied low reference circuit:
- IAT sensor 1
- IAT sensor 2
- Humidity sensor
- Barometric pressure (BARO) 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) |