Engine Coolant Temperature Sensor - Operation

ENGINE COOLANT TEMPERATURE SENSOR

At key-on, the Powertrain Control Module (PCM) sends out a regulated 5 volt signal to the engine cooant temperature (ECT) sensor. The PCM then monitors the signal as it passes through the ECT sensor to the sensor ground (sensor return).

When the engine is cold, the PCM will operate in Open Loop cycle. It will demand slightly richer air-fuel mixtures and higher idle speeds. This is done until normal operating temperatures are reached.