September 30: LEMON manuals is back up on a temporary server! Slowness is possible
Engine Coolant Temperature
- The engine coolant temperature (ECT) sensor 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 Engine Coolant Temperature (ECT) sensor is threaded into an engine coolant passage.
- The ECT sensor is similar in construction to the IAT sensor.