Circuit/System Description

The sensors listed below are integrated within the multifunction intake air sensor:

• Intake Air Temperature (IAT) sensor 1
• IAT sensor 2
• Humidity sensor
• Mass Air Flow (MAF) sensor
• Barometric (BARO) pressure sensor

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 signal circuit is shared by the IAT sensor 2 and the humidity 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

Ignition voltage and ground circuits are also supplied to the multifunction intake air sensor's internal circuits for the mass air flow (MAF) sensor.