Circuit Operation

A 5-volt reference voltage is applied to the intake air temperature sensor output terminal (terminal No. 6) from the PCM (terminal No. 99) via the resistor in the PCM. The ground terminal (terminal No. 5) is grounded with PCM (terminal No. 88). The intake air temperature sensor is a negative temperature coefficient type of resistor. When the intake air temperature rises, the resistance decreases. The intake air temperature sensor output voltage increases when the resistance increases and decreases when the resistance decreases.