Engine Coolant Temperature (ECT) Sensor
WARNING: This page is about a different car, the 2008 Ford Pickup, 2008 Ford F550 Super Duty, 2008 Ford F450 Super Duty, and 2008 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The Engine Coolant Temperature (ECT) sensor is a 2-wire thermistor which changes resistance as temperature changes. The resistance of the sensor increases as engine temperature decreases and the voltage measured by the PCM increases. The PCM uses this information to determine Torque Converter Clutch (TCC) operation.