Theory Of Operation
WARNING: This page is about a different car, the 2013 Jeep Patriot and 2013 Jeep Compass. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Control Module (TCM) monitors the Transmission Temperature Sensor Signal circuit for voltage changes within desired limits. The TCM calculates the transmission fluid temperature from the temperature sensor signal voltage. This value is used in conjunction with various other inputs to calibrate different operating modes such as Torque Converter lock-up and Torque reduction.
The Transmission Temperature Sensor is a thermistor that changes resistive value when subject to different temperatures. When the monitored voltage rises, the calculated temperature decreases.