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

Engine Coolant Temperature (ECT) Sensor:

PURPOSE
The Engine Coolant Temperature (ECT) sensor constantly supplies the Powertrain Control Module (PCM) with a signal reflecting engine coolant temperature. The PCM reads varying sensor resistance and determines engine operating temperature. This information is used in calculations for air/fuel mixture, idle speed, and purge flow.

OPERATION
The ECT is a negative temperature coefficient thermistor sensor. As coolant temperature increases, sensor resistance decreases, and vice versa.