Coolant Temperature Sensor/Switch (For Computer): Description and Operation

REMOVAL
The Engine Coolant Temperature (ECT) Sensor threads into the coolant outlet connector. The ECT Sensor is a negative thermal coefficient sensor.

OPERATION
The ECT sensor provides an input to the PCM. As temperature increases, resistance of the sensor decreases. As 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. The PCM uses ECT sensor input to send messages over the PCI bus to various modules for other functions such as temperature gauge and AC operation.