Air Temperature Sensor ( Ambient / Intake ): Description and Operation

PURPOSE
The sensor element extends into the incoming airstream to measure the temperature of the air passing through the intake manifold.

OPERATION
The Powertrain Control Module (PCM) sends out a reference voltage of approximately five (5) volts to the coolant temperature sensor. As air temperature changes, the internal resistance of the sensor will change, causing a varying voltage drop across the sensor. The PCM reads the voltage drop across the sensor as charge air temperature.

The PCM uses this information to calculate the proper injector pulse width and spark advance.

CIRCUIT OPERATION
The intake air temperature sensor provides an input to the Powertrain Control Module (PCM) on circuit K21. The K21 circuit connects to cavity 37 of the PCM connector.

From circuit K21, the intake air temperature sensor draws voltage from the PCM. The sensor is a variable resistor. As intake air temperature changes, the resistance in the sensor changes, causing a change in current draw.

The PCM provides a ground path for the intake air temperature sensor signal (circuit K21) through circuit K4. Circuit K4 connects to cavity 43 of the PCM connector.