Charge Air Cooler (CAC) Coolant Temperature Sensor

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The CAC coolant temperature sensor is a thermistor device in which resistance changes with the temperature. The resistance of a thermistor decreases as temperature increases, and the resistance increases as the temperature decreases. The varying resistance affects the voltage drop across the sensor terminals and provides electrical signals to the PCM corresponding to temperature.

Thermistor-type sensors are considered passive sensors. A passive sensor is connected to a voltage divider network so varying the resistance of the passive sensor causes a variation in total current flow. Voltage that is dropped across a fixed resistor (pull-up resistor) in series with the sensor resistor determines the voltage signal at the PCM. This voltage signal is equal to the reference voltage minus the voltage drop across the fixed resistor.

The CAC coolant temperature sensor is installed in the side of the CAC radiator and measures the CAC system coolant temperature. The PCM uses the CAC coolant temperature sensor to determine desired operating condition of the CAC coolant pump.

Fig 1: Identifying Charge Air Cooler Coolant Temperature Sensor

Courtesy of FORD MOTOR CO.