I'm not familiar with your particular unit, but if it's anything like my 2013 Alpine, check for a switch mounted inside your battery compartment, or possibly your propane locker. It is probably be where it's convenient to access while hitching/unhitching, but still out of, and protected from the weather.
Mine has a switch plate labeled "DOCKING LTS". See thumbs...
Hope this helps, Good Luck!
Steve & Jan, Ava & Emma (Mini Schnauzers):
2016 F350 Lariat 4X4 Powerstroke CC/SB "PULLTOY V"
2013 Alpine 3535RE "MAGIC CARPET IV"
Proud Navy Vet!