Circuit Description
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 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 part of the transmission pressure switch manifold assembly. The TFT sensor is a thermistor which changes its value based on temperature. The Transmission Control Module (TCM) supplies a 5-volt reference signal to the TFT sensor. When the transmission fluid is cold, the sensor resistance is high and the TCM detects a high signal voltage. As transmission fluid temperature increases, the resistance becomes less, and the signal voltage decreases.
This is a type "B" DTC.