[hypoxia]

I was wondering why I might turn that switch on.  Now I realize I would re-label it to "Increase Rear Height Clearance".  When I turn that switch on it changes the tag air spring (airbag) from around 75 PSI to 115 PSI or whatever the compressor is putting out.  The net result is the rear end roller by the trailer hitch is about 2" higher giving better ground clearance.  I put some mileage on that roller in Duluth and Gallup this summer prior to realizing what the switch does.