E 150 V8-4.6L SOHC VIN W (2004)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
ENGINE COOLANT TEMPERATURE SENSOR
Typical Engine Coolant Temperature (ECT) Sensor
The engine coolant temperature (ECT) sensor (Figure 33) is a thermistor device in which resistance changes with temperature. The electrical resistance
of a thermistor decreases as the temperature increases, and increases as the temperature decreases. The varying resistance affects the voltage drop across
the sensor terminals and provides electrical signals to the PCM corresponding to temperature.
Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so that varying the resistance of the
passive sensor causes a variation in total current flow.
Voltage that is dropped across a fixed resistor in a series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to
the reference voltage minus the voltage drop across the fixed resistor.
The ECT measures the temperature of the engine coolant. The sensor is threaded into an engine coolant passage. The ECT sensor is similar in
construction to the IAT sensor.
