ECT

Scan Tool Range -40°C to 151°C, -40°F to 304°F. The Engine Coolant Temperature (ECT) sensor is mounted in the coolant stream. The PCM applies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold, indicating that internal resistance is high, the PCM monitors a high signal voltage and interprets it as a cold engine. As the sensor warms, or as the internal resistance decreases, the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.