The one in my unit is located on the panel with the rocker switches for lights/water pump/water heater/awning/slideout, etc. It's a silver knob; out is on and in is off.
For some models, it's in the storage compartment.
Hope this helps.
2012 Fun Finder XT 276 Toy Hauler & Harley Davidson Ultra Classic with Condor wheel chock
2014 Dodge Ram 2500 AT 4X4 Crew Cab 6.4 L Hemi, 373 gears, tow package, Rambox option, Revolver X2 tonneau cover, Equal-I-zer anti-sway hitch.