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

Reference Data:

The engine coolant temperature sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the PCM. The modified signal returns to the PCM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.

CAUTION: Do not use PCM ground terminals when measuring input/output voltage. Doing so may lead to PCM's transistor damage. Use ground other than PCM, such as engine ground.