The bulkhead disconnect is on the firewall, under the hood, just to the left of the brake M/C and below it. But it has nothing to do with the dash lights as you describe. 1969383S has you covered.
Do not take any metal tools under there, until you figure out where the ammeter is, and how to stay away from the exposed hot terminals on the back of it. They are live at all times, and if you short one to ground, you will have a major light show.
