Tail light won't turn off...

I have a '79 XS400 that I've been restoring. I hooked up the new battery, installed a new fusebox (Properly, and same as the stock one) and the tail light won't shut off. The tail light problem was there prior to the new battery and fuse box, though. I can disconnect both of the wires from the brake switch, and the brake light still stays on as if it's getting it's power from somewhere else. Thoughts, anyone? Fairly new to this, so I'll take all the help I can get.

Zach

Which brake switch did you disconnect? Is the rear switch operating normally as well?

Is it the tail light or the brake light?

Brake light. When I disconnect the yellow (brake light) wires from the tail light itself, the tail light stays on
As soon as I plug the yellow ones back in, the brake lights are back on.

Levdir, I detached the rear brake switch to check continuity and everything was good
The switch operates properly as well.

Check out your front brake light switch too.