Celica Coupe L4-107.5 1762cc 1.8L DOHC (7A-FE) (1995)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
PURPOSE
The engine coolant temperature (ECT) sensor monitors coolant temperature with a thermistor whose resistance varies according to engine
temperature The engine control module (ECM) uses this signal to control open/closed loop operation of the fuel injection system, overdrive on
electronic transaxles, electronic spark advance, idle speed control system and other functions.
OPERATION
The ECM sends out a reference voltage of approximately five (5) volts to the ECT sensor. As coolant temperature changes, the internal resistance
of the sensor will change, causing a varying voltage drop across the sensor. The ECM reads the voltage drop across the sensor as engine coolant
temperature