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

LOCATION

The sensor is located near the thermostat housing.


OPERATION

The engine controller receives information regarding engine operating temperature from the coolant temperature sensor. Engine coolant temperature is the same as engine operating temperature.

The sensor is a variable resistor. As coolant temperature varies, the coolant temperature sensors resistance changes. This results in a different input voltage to the engine controller.

The engine controller contains different spark advance curves for different engine operating conditions. There are unique spark advance schedules for cold and warm engine operation that have been added to reduce engine emission and improve driveability. The engine controller will supply slightly richer air-fuel mixtures and higher idle speeds until normal operating temperatures are reached.

All spark advance testing should be done with the engine fully warmed.