Engine Coolant Temperature Sensor
WARNING: This page is about a different car, the 2003 Dodge Intrepid, 2003 Chrysler Intrepid, 2003 Chrysler Concorde, and 2003 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.
The Engine Coolant Temperature (ECT) sensor threads into the coolant system. See Figure or Figure . The ECT sensor provides an input to the PCM. As coolant temperature varies, the ECT sensor resistance changes resulting in a different input voltage to the PCM. When the engine is cold, the PCM will demand slightly richer air/fuel mixtures and higher idle speeds until normal operating temperatures are reached. The ECT sensor input also determines operation of the low and high speed fans.