nerd harness help

So i have a 2016 base model explorer V6 4wd... i put a hitch on to tow a small trailer and a mobility scooter... install went fine til i got to the harness.. i got the t-one connector assembly ..part #118540 .. so there was supposed to be a plug to undo and then connect the harness to the 2 connectors... well on my explorer there was nothing plugged into the vehicles connector so i plugged the wiring harness in and taped off the open plug since there was nothing to plug into it.. checked the harness and it only works woth the left turn signal.. dont work with brakes or running lights turned on... i dunno what to do here... please help ..

 

[Biohazrus]

I would give a shot at testing the harness you are try to put on.
Kind of stupid check, make sure there is continuity and your "new" harness ain't DOA.
Then if that looks good, I put the multimeter in the original plug and confirm there is current there.
Also, might be a grounding issues (throwing it out, just in case)

But I just looked at an install guide and you would be suppose to have something plugged in the other connector...
No clue where this other is going, but might explain why it is not working!?!?!