Pulsar L4-1597cc 1.6L SOHC (GA16i) (1990)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Fig. 83 Water Temperature Sensor
The water temperature sensor, located in the intake manifold, uses a thermistor which changes in resistance according to the coolant temperature.
As the temperature rises the resistance of the sensor lowers. The ECU interprets the resistance value as engine temperature.