Transmission Fluid Temperature Sensor
WARNING: This page does not describe the selected car, but rather 33 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
The Transmission Fluid Temperature (TFT) sensor is a thermistor (temperature sensitive resistor). PCM supplies and monitors a 5-volt reference signal through an internal resistor to sensor. Monitored voltage is high when temperature is low (high sensor resistance), and low when temperature is hot.