What's this electrical box and/or connector?

I have a new to me 2007 Tundra 5.7 SR5 4x4 and looking into cleaning up a few shoddy things on it, one of them is finding out what this electrical panel is under the hood, then finding out what the circled connector is, then finding out what the black wire in that connector is, since it currently has a power jumper wire ran to it from the battery. Is this a mod of some sort or a hack?

Does anyone know what the connectors in this electrical panel are labeled/numbered as or what they're for? I do have the electrical system pdf with connector labels but they don't show location. Any help is greatly appreciated thanks!

 

So the jumper wire that runs across from the battery has a 30 amp fuse in it. I pulled the fuse out and started the truck to see what happens. Started right up, no CEL, everything appeared to still work. (other than the clock/info, I need to do the mosfet fix).

The only thing I'm thinking is maybe it's somehow related to the brake controller? The controller still powered on but I didn't know how to test it sitting in the garage.

 

Welp, just cut the little ziptie and pulled the wire out from being jambed in the back of that connector and took it off the battery post and threw it away. Not sure what it was for but I guess we'll find out if I need it!

 

If your Tundra came with the tow package then it would have factory wiring for the brake controller. I just got a used 2007 and someone put in an amp and sub woofer. They took the sub out but left the wiring and fuse. Inside the truck it was a clear blue heavy gauge wire but under the hood it was just brown from age. They also installed a box to convert the output of the stereo (to the speakers) into something the amp could handle (using RCA style cable). I had to pull the stereo to remove the box. So my guess would be something to do with the stereo or possibly a remote starter. Either way it amazes me how poorly some people do work. On my truck the guy used a sheet rock screw through the fuse box cover to hold the fuse for the amp in place. Just jamming a wire into a connector and then using a ziptie to hold it has to be one of the laziest wiring jobs I have seen to date. If it was for a brake controller that would of been an accident waiting to happen as sooner or later it wasn't going to make contact.

 

I still can't explain what this wire was for. Everything still works. I found a missing plug to get my dash clock and stereo working so I could remove the jank stereo power jumper. Heated seat add a fuses instead of wires jammed into fuse slots. Removed bed topper light loose power wire. I think it's all cleaned up wiring wise now!