Transmission Fluid Temperature Sensor

WARNING: This page is about a different car, the 2003 GMC Sierra and 2003 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The automatic Transmission Fluid Temperature (TFT) sensor is part of the automatic Transmission Fluid Pressure (TFP) manual valve position switch. The TFT sensor is a resistor or thermistor, which changes value based on temperature. The sensor has a negative temperature coefficient. This means that as the temperature increases, resistance decreases and as temperature decreases, resistance increases. The PCM supplies a 5-volt reference signal to TFT sensor and measures voltage drop in the circuit. When transmission fluid is cold, sensor resistance is high and PCM detects high signal voltage. As fluid temperature warms to a normal operating temperature, resistance becomes less and signal voltage decreases.

PCM uses TFT sensor input to control Torque Converter Clutch (TCC) application and shift quality. Sensor circuit problem should set a related DTC.