Gonein60

Bringing a '75 up to date. I have a short somewhere in my pos (tan) cowl solonoid wire. In pursuing running a new wire from the gas pedal switch to the plug-in under front of the hood, I found a black flat plastic piece under dash, near firewall with 3 tan wires attached to it. Two tan wires come into one side of the back, and one tan wire comes into the other side of the back. The piece has a metal front with a black button-looking tab in the middle. The tab doesn't move. Any one know what this piece is, and whether it has any connection to the tan cowl wire? May have something to do with my short.
Thanks