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

CIRCUIT OPERATION
The engine coolant temperature sensor provides an input to the Powertrain Control Module (PCM) on circuit K2. This vehicle uses a separate sensor for the instrument cluster coolant temperature gauge.

From circuit K2, the engine coolant temperature sensor draws up to 5 Volts from the PCM. The sensor is a variable resistor. As coolant temperature changes the resistance in the sensor changes, causing a change in current draw. The K2 circuit connects to cavity 16 of the PCM connector. The PCM provides a ground for the engine coolant temperature sensor signal (circuit K2) through circuit K4. Circuit K4 connects to cavity 4 of the PCM.

When the coolant temperature is above a pre-determined temperature, contacts in the engine coolant temperature switch CLOSE and circuit G6, from the lamp, is connected to ground through circuit G2 and the case grounded switch.