Temperature Sensor (Gauge): Description and Operation

The engine coolant temperature indication system is a magnetic-type indication system consisting of:
- the water temperature indicator sender unit located in the engine block or cylinder head
- an Engine Coolant Temperature Gauge in the instrument cluster

The water temperature indicator sender unit operates as follows:
- changes resistance according to engine coolant temperature, which varies the current flow through the engine coolant temperature gauge.
- the pointer position varies proportionally to the current flow.
- resistance is high when the engine coolant temperature is low, and low when the engine coolant temperature is high.
- the pointer of the magnetic engine coolant temperature gauge remains in position when ignition switch is turned to OFF.
- pointer will move to the correct indication whenever the ignition switch is turned back to RUN.
- pointer may indicate at the top of the normal band with the engine coolant temperature within specification, under certain driving conditions such as heavy traffic or stop-and-go driving in hot weather.

WATER TEMPERATURE INDICATOR SENDER UNIT
The water temperature indicator sender unit is mounted into the thermostat housing bypass tube. The signal sent to the Engine Coolant Temperature Gauge varies with the resistance of water temperature indicator sender unit, which depends on the engine coolant temperature.