Engine Coolant Temperature (ECT) Sensor
WARNING: This page is about a different car, the 2002 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
The Engine Coolant Temperature (ECT) sensor detects temperature of engine coolant and supplies the information to the Powertrain Control Module (PCM). The ECT sensor is used to control Torque Converter Clutch (TCC) operation.