K 3500 Truck 4WD V8-454 7.4L (1994)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature (ECT) Sensor Circuit
Purpose:
The Engine Coolant Temperature (ECT) sensor is a thermistor that is located in the engine coolant flow. When the coolant temperature is low, the
sensor produces a high resistance. When the coolant temperature is high, the sensor produces a low resistance.
The control module sends a 5 volt signal to the ECT through a resistor in the computer and measures the voltage. The voltage will be high or low
depending on coolant temperature. By varying the voltage the computer can determine engine coolant temperature.
