Engine Temperature Sensor: Description and Operation

Coolant Temperature Sensor
Incorporated with coolant temp. gauge and installed to thermostat case, this sensor measures the temperature of the engine coolant and converts its change into that in resistance through the thermistor like the air temperature sensor. That is, as coolant temperature lowers, resistance increases and as it rises, resistance decreases. By monitoring the resistance of the coolant temperature sensor, ECM detects the engine coolant temperature and that affects most systems under the control of ECM.





Engine Coolant Temperature Signal Output for A/T
ECM transmits the engine coolant temperature signal to Transmission Control Module by grounding signal terminal which receives battery voltage from TCM. TCM uses this signal as one of the factors to control shift to the 4th (O/D) gear, TCC and A/T throttle pressure.