Evergreen Element SRL electrical outlet issue

[DGriff]

Thanks to everyone for your replies.We tried tracing the cord that plugs directly into the inverter output outlet(that is an original install) to see where it goes/what it is supposed to power. It runs out of the inverter, around the back of the trailer under a seat bench, goes under the trailer, runs along the frame underneath and then back up into the trailer into a sealed section that is behind the bathroom which we haven't been able to access from either inside or outside of the trailer. So we really haven't been able to figure out where it ends. We didn't see any type of automatic transfer switch along the part of the line we could see. We traced the other power lines that were coming out of that sealed space behind the bathroom to the batteries and no transfer switch-just a junction box near the hitch which we opened up-just basic wires. We traced the input power lines to the inverter back to the batteries and no transfer switch along there either. We called WFCO and there is not an automatic transfer switch built into that unit and we pulled the whole WFCO unit and there is no transfer switch behind it. We called the dealership where we purchased the trailer and they weren't any help. We've also looked at the manuals we have and haven't found any further info.

We tried an experiment-took the cord that usually plugs into the output of the inverter and plugged it into a running generator to simulate shore power(Trying to figure out what the cord is supposed to power). We plugged a small lamp into an outlet and when we turned it on the light didn't come on but we heard a loud click/swish type of noise- in the area behind the bathroom that we traced the cord to and aren't able to access. Does this give any clues? To us it makes no sense that an automatic transfer switch would be put in a place that has no access-if that's what was making the noise- so we're going to look again to see if we missed some type of access panel.
We're at a loss. We really don't know what that cord that plugs into the inverter is supposed to power if it's not at least some of the outlets. We're starting to question if we remember correctly that we have used the outlets while dry camping, but we are almost certain we have-especially the one for the TV. We know the heater blower runs directly on DC-tested it, and the refrigerator can switch between regular AC, DC, and propane so no need for an inverter there.
We really appreciate everyone's time and thoughts on this-thanks again!