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

Coolant Temperature Sensor:

PURPOSE
Informs ECU of engine coolant temperature fluctuations.

OPERATION
The sensor is a temperature sensitive resistor with a negative temperature coefficient. As engine temperature increases, sensor resistance decreases. Resistance changes are interpreted by the ECU as engine temperature fluctuations. When temperatures are within ECU programmed parameters, air/fuel ratio will be enriched during cold start and warm-up by increasing injector "ON" time. Sensor voltage signal at the ECU is approximately 2.06V at 86°F (30°C).

The coolant temperature sensor, idle speed control valve and supplementary air valve perform together as the functional equivalent of a carburetor automatic choke.

LOCATION
Rear of thermostat housing.