Mystery Box Under Carpet

Hi, I have a very minor problem where the dome light comes on when I hit the brakes, first thing I did was order new door switches, while waiting for them to come in the mail I decided to take the plastic panels off and inspect the wiring in the tail light area, while doing this I found a small metal box thats rusted through on the bottom with one of the wires clipped, probably due to my leaking hatch and taillights. Any idea what this box could be? I was also unable to find any ground wires to check.

Heres a couple pictures I took: