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.

OPERATION
The ECT is a negative temperature coefficient sensor. As coolant temperature increases, sensor resistance decreases, and vice versa. The PCM reads varying sensor resistance and determines engine operating temperature. This information is used in calculations for air/fuel mixture, idle speed, fuel pressure, purge flow, and ignition timing.