2002 Tundra - Trying to Identify Harness

Hello,
This is my first time posting on this forum. I wasn't sure if this should fall under the "1st gen" forum or here. Some backstory, I own a 2002 Toyota Tundra Limited, Access Cab. I am the second owner. My car was rear ended in a parking lot, but there was no major damage, just lost my passenger side tail light. Thought this would be an easy fix, I was wrong. Turns out I needed a new wiring harness for the tail light because the one on it was rigged to accommodate the after market lights the truck had at the time (it had these lights when I bought it). The tail light, bulbs, and wiring harness were replaced without issue and worked for a few weeks. Then my brake light stopped working on the passenger side (the side that was replaced). So I replaced the bulbs just in case, checked the harness and everything, then the drivers side brake light stopped working. A neighbor of mine who works on his cars determined it is due to another harness/assembly that the tail light harness connects to. When I replaced it, it must have short circuited it. The issue is, I do not even know what this harness is called and searching for it so I can replace it has turned up nothing. The harness/assembly connects to the tail light assembly and ends under my driver's seat, so it's pretty long. Does anyone know what it is called or where I can find a replacement? I've searched various site and have not found it. I would greatly appreciate the help.
Thanks

****To clarify, neither brake light is working now or my reverse lights for both sides

 

Did you replace both of the aftermarket taillights with OEM style? Do they both match?

 

Randomly replacing harnesses isn’t the way I would go about it. If your factory pigtail harness at the lights was modified I would replace those, both of them. Then before plugging the lights in, I would check all the fuses and test the harnesses to ensure function before moving on to a more central harness. The harness, unless newly damaged physically can’t just “short out”. That would blow a fuse, not ruin a harness.