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

Coolant Temperature Sensor (Typical):

PURPOSE

Engine controller uses input to:

^ Adjust fuel injector pulse width, (cold engine receives a longer pulse width, for a richer mixture).
^ Maintain warm-up idle speed.
^ Control radiator fan.

OPERATION

Engine controller provides sensor reference voltage of approximately five (5) volts.
Sensor maintains constant contact with engine coolant. As coolant temperature changes, internal resistance of sensor changes, resulting in varying voltage drop across sensor.