Do you see a fuse or breaker labeled for anything that might relate to it? It would seem logical that if the factory thought ahead enough to provide the pre-wiring for some device, they also would have pre-wired it through some fuse or breaker to protect that device. A multi-tester would tell you pretty quickly if one of the wires is hot and/or if one is already grounded to the camper's grounding system. You could check 12V DC without the camper connected to shore power then connect to shore power to check for 120V AC. Either way, extra factory installed wiring is a gift! Once you find where the other end is, you never know what job(s) you'll find for it to do (to power small interior fan, AM/FM radio, HAM radio, TV, smart device charger, privacy reading light
, etc., etc., etc). The original owners of our EggCamper
installed three 12V deep cycle batteries on the tongue and ran a dedicated pair of marine-grade, tinned, 8 gauge wires from the batteries back through the wall and cabinets to a 1000 watt pure sine-wave inverter back near the bed to power two CPAP breathing assistance machines through the night while boondocking
. We took out the inverter and use those wires to power our 12V DC TV and a small fan over the bed. We might not have added those if the wiring wasn't already in place. For what it's worth, we now travel with only two of the three batteries just to lighten the tongue weight
a bit, and I'm sure we could get by with just one if we needed to lighten it more.