TR Sensor
WARNING: This page is about a different car, the 2016 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
The TR sensor is located inside of the transmission and indicates gearshift position to the PCM. The PCM uses that information to enable the starting system to start the engine in PARK or NEUTRAL. Refer to Automatic Transmission 6R80 for more information.