Trailer Reversing Lamps
WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
When the transmission is in REVERSE and the ignition is in RUN, the BCM provides voltage to the trailer tow reversing lamps relay coil. Once the trailer tow reversing lamps relay coil is energized, the relay supplies voltage to the trailer tow connector for trailer reversing lamps.