The engine coolant temperature sensor resistance changes in response to engine coolant temperature. The sensor resistance decreases as the surrounding temperature increases. This provides a reference signal to the PCM, which indicates engine coolant temperature.
The ECT sensor is mounted on the lower intake manifold near the water outlet/thermostat housing, except on 2.3L and 2.5L engines. On the 2.3L and 2.5L engine the ECT is mounted on the water outlet/thermostat housing.
The Engine Coolant Temperature (ECT) sensor sends the PCM a signal indicating engine temperature. The voltage signal from the ECT decreases as coolant temperature increases.