SRX 2WD V8-4.6L VIN A (2004)
Intake Air Temperature (IAT) Sensor: Description and Operation
AIR TEMPERATURE SENSORS
The air temperature sensors are 2-wire negative temperature co-efficient thermistors. The vehicle uses the following air temperature sensors:
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Ambient
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Inside
A signal and low reference circuit enables the sensor to operate. As the air temperature surrounding the sensor increases, the sensor resistance
decreases. The sensor signal decreases as the resistance decreases. The sensor signal varies between 0-5 volts. The HVAC control module converts
the signal to a range between 0-255 counts.
The inside temperature sensor operates within a temperature range between -6.5°C and 57.5°C (20.3-135.5°F). if the sensor is shorted to ground,
voltage, or an open, the system will operate using an estimated default value to allow the system to operate. The ambient sensor operates within a
temperature range between -30 to 51 °C (-22 to 123.8°F). If the HVAC control module has determined that the ambient temperature sensor has failed,
the driver information center (DIC) display shall display 59°F in place of the outside air temperature. If the sensor is shorted to ground, voltage, or an
open, the system will operate using an estimated default value to allow the system to operate. If the engine coolant temperature is not more than 3°C
(5.4°F) above the sensor reading, or if the engine has not been started in 3 hours, then the actual ambient air temperature sensor reading is displayed.
Also at vehicle speeds greater than 35 km/h (22 mph), the ambient air temperature displayed may be allowed to increase, but only at a slow, filtered
rate. The driver information center (DIC) displays the ambient air temperature value that it receives from the HVAC control module through a class 2
message. The ambient air temperature value can be updated by an outside air instant update feature.
To use this feature, press the following switches on the HVAC control module simultaneously:
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AUTO
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MODE UP
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LEFT TEMPERATURE UP
