Trailer wiring woes....

I just bought a 1999 Ford Explorer XLT as a temporary substitute for my regular tow vehicle, while it gets restored. Problem is, the OEM trailer connector under the bumper is dead; from what I learned, the previous owner never used it. I checked the usual; not used to all this extra electrical wiring! The noted trailer fuses test good, both inside & under hood. A trailer relay is noted, but I can't find it-what does it do? Tried to find wiring diagram for vehicle as .pdf, but not successful yet. Can anybody help with this problem? Ideas? I need to use utility trailer (with new LED lighting!) to pick up more insulation; I am cold!!! Thanks for your help?
khg

 

[Mbrooks420]

Did you pull it from the connector up under the taillight and reseat? Done Explorers have the red capped plug on both sides, of double check to make sure you don’t have a second plug in, and try that if you do.

 

[Kenny G.]

Did you pull it from the connector up under the taillight and reseat? Done Explorers have the red capped plug on both sides, of double check to make sure you don’t have a second plug in, and try that if you do.

Thanks! Will do that soon as the snow stops!