Circuit/System Description
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The transmission fluid temperature (TFT) sensor is a 2 wire sensor located in the pressure switch manifold (PSM). The transmission control module (TCM) supplies 5 V on the signal circuit and a ground circuit to the TFT sensor. The resistance of the TFT sensor decreases as the oil temperature increases. The TCM monitors the voltage drop across the TFT sensors and calculates the temperature of the transmission oil in the oil pan.