Engine Coolant Temperature (ECT) Sensor

ECT sensor contains a built-in thermistor in which resistance varies according to engine coolant temperature. ECT sensor delivers an input signal to THW terminal of Engine Control Module (ECM). ECM may use input signal for determining ignition timing (spark advance) and for controlling fuel injection system, engine idle speed control system, heated oxygen sensor system and operation of electronically controlled transaxles/transmissions. For ECT sensor location, see ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article.