Temperature Sensor (Gauge): Description and Operation

ENGINE COOLANT TEMPERATURE METER AND ECT SENSOR
The engine coolant temp. meter is located in the instrument panel and its sensor (sender gauge) on the inlet manifold.

The sender gauge shows different resistance values depending on the coolant temperature. This causes a current flowing through the temperature meter coil to change, controlling the meter pointer. That is, when the coolant temperature rises, the sensor resistance is decreased with more current flowing through the meter coil, thus allowing the meter pointer to move away from the "C" position.