OEM towing package lights

Long story short, my new to me ‘01 double cab has two trailer pigtails. One is aftermarket (that works, somewhat), the other is OEM that does not work. I traced the OEM from the back of the truck to the converter box that is in the cab on the back driver wall. After some prodding around I realized all the fuses were good but the box has no power. Traced the wiring from the box towards the front of the truck and found it dead ended under the driver seat. Both plugs from the box were plugged in to each other. There are no other connectors under the driver seat that they could plug in to.

Does anyone have any idea what harness would be needed for it to work? Or where the other end of the harness would originate from? I’m assuming a PO must have had problems and taken it out for some reason. Or maybe they coiled the other end up and tucked away somewhere. I’ve attached a picture of the plugs I found under the drivers seat.

 

my only thought is along the door sill cover. probably would be in there/along there judging by the length of the wires you are holding