Previa Van LE 4WD L4-2438cc 2.4L DOHC SC MFI (1997)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Figure 1
Reference
CIRCUIT DESCRIPTION
A thermistor built into the engine coolant temperature sensor changes the resistance value according to the engine coolant temperature.
A thermistor built in the sensor changes the resistance value according to the intake air temperature. The lower the intake air temperature, the
greater the thermistor resistance value, and the higher the intake air temperature, the lower the thermistor resistance value (See Fig. 1.).
The intake air temperature sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the intake air temperature
sensor from the terminal THW via a resistor R.
That is, the resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor
changes in accordance with changes in the intake air temperature, the potential at terminal THW also changes. Based on this signal, the ECM
increases the fuel injection volume to improve driveability during cold engine operation.
