It would be somewhere in the lower half - mine is next to the refrigerator. It will be located in the same area as the inside fuse panel, if you've found that. You could also trace the shore power cord to it. I can't be more specific since they are in somewhat different positions depending on your model.
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Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew