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

The engine coolant temperature sensor is a variable resistor with a range of -40 °C - 129 °C (-40 °F - 265 °F).

Fig. 4 Engine Coolant Temperature Sensor:

The coolant sensor threads into the top of the thermostat housing. New sensors have sealant applied to the threads.

The engine coolant temperature sensor provides an input voltage to the PCM. As coolant temperature varies, the coolant temperature sensor resistance changes resulting in a different current draw from the PCM.

When the engine is cold, the PCM will demand slightly richer air/fuel mixtures and higher idle speeds until normal operating temperatures are reached.

The coolant temperature sensor has one element. The element supplies coolant temperature signal to the PCM. The PCM supplies coolant temperature information on the CCD Bus to the Body Control Module (BCM) for the instrument panel gauge cluster.

The engine coolant sensor is also used for cooling fan control.