Coolant Temperature Sensor/Switch (For Computer): Description and Operation

Fig. 42a Water Temperature Sensor.:

The water temperature sensor, incorporated into the thermostat housing, Fig. 42a, monitors change in cooling water temperature and transmits a signal for the fuel enrichment to change the pulse duration during warm-up.
The temperature sensing unit employs a thermistor which is very sensitive in the low temperature range.

Fig. 42c Water Temperature and Air Temperature Sensor Graph.:

The electrical resistance of the thermistor decreases in response to the rise in water temperature.