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

Engine Coolant Temperature (ECT) sensor:

PURPOSE
The Engine Coolant Temperature (ECT) Sensor, located in the cylinder head just below the distributor, delivers an electrical signal to the Programmed Fuel Injection Electronic Control Module (PGM-FI ECM) allowing it to adjust the length of injector opening time required by the engine for optimum performance at all engine temperatures.

OPERATION
As water temperature increases, sensor resistance decreases. The PGM-FI ECM receives sensor information as resistance to ground. Coolant temperature information is used by the PGM-FI ECM to determine proper fuel delivery.