OK, since the make and model of your 5th wheel is not listed your profile, the title or your post, you need to provide that information.
Inverter locations vary between make and model.
Having that info will get you directed to best place for help.
Dan-Retired California Firefighter/EMT
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package