Paseo Coupe L4-1497cc 1.5L DOHC MFI (1997)
Engine Coolant Temperature Switch (For Computer): Description and Operation
Figure 1
CIRCUIT DESCRIPTION
A thermistor built into the engine coolant temperature sensor changes the resistance value according to the engine coolant temperature.
The lower the engine coolant temperature, the greater the thermistor resistance value, and the higher the engine coolant temperature, the lower the
thermistor resistance value (See Fig. 1.).
The engine coolant temperature sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the engine coolant
temperature sensor from the terminal THW via a resistor R.
That is, the resistor R and the engine coolant temperature sensor are connected in series. When the resistance value of the engine coolant
temperature sensor changes in accordance with changes in the engine coolant 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.
