Intake Air Temperature Sensor Testing

Operation

The intake air temperature sensor functions to convert the temperature of the air (intake to the engine) to voltage, and to input that voltage (as signals) to the engine control module. The engine control module, based upon those signals, then corrects the amount of fuel injection, etc.

The 5V power supply within the engine control module is supplied, by way of the resistance within the unit, to the intake air temperature sensor; it passes through the intake air temperature sensor, which is a type of resistor, and is grounded at the engine control module. Note that the resistance of the intake air temperature sensor decreases when the temperature of the intake air increases.

The intake air temperature sensor terminal voltage becomes higher when the resistance of the intake air temperature sensor increases, and becomes lower when the resistance decreases. Consequently, the intake air temperature sensor terminal voltage varies in accordance with the temperature of the intake air, becoming lower when the temperature of the intake air increases.



TROUBLESHOOTING HINTS

Because the intake air temperature sensor detects the temperature of the intake air in the air cleaner, it indicates a temperature different than the temperature of the outside air when the engine is running.




INSPECTION USING A SCAN TOOL




HARNESS INSPECTION


SENSOR INSPECTION

1. Disconnect the volume air flow connectors.











2. Measure resistance between terminals 4 and 6. Measure resistance while heating the sensor using a hair drier.
3. If the value deviates from the standard value or the resistance remains unchanged, repalce the volume air flow sensor assembly.