The Engine Coolant Temperature (ECT) sensor provides an input to the Powertrain Control Module (PCM). As the temperature increases, the resistance of the sensor decreases. As the coolant temperature varies, the ECT sensor resistance changes resulting in a different voltage value at the PCM ECT sensor signal circuit. The ECT sensor provides input for various PCM operations. The PCM uses the input to control air-fuel mixture, timing, and radiator fan on/off times.