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

There are three devices which send coolant temperature information to the ECU. They are the coolant temperature sensor, coolant temperature switch, and the thermo time switch. All three devices are located in the water jacket of the engine block.
The ECU interprets the signals from these sensors as cold or normal operating temperatures. During cold operating conditions, the air/fuel ratio is richened by the cold start valve for starting, and the injectors while warming to normal operating temperature.