Why not cook marshmallows on my under dash fire?

Now back to info that I will need. I am finishing up the wiring at my fuse block. On the wiring diagram it shows where the connectors hook onto the block. The wire that caused my entire problem from the beginning wasn't hooked to anything but the power on my fuse block. (It was grounding out on the body of the car) that wire doesn't show up on the wiring diagram and I am trying to figure out if it had a purpose that the wiring diagram may not show.

Also, does anyone have anything bad to say about the autozone ignition switches?