Originally Posted by Gottagofast
Back trace the wires to the splice... remove it and repair the wiring.
Create a new circuit for the lightbar w a new switch on the dash.
^^^ What he said.
Remove all the PO's wiring. Start fresh.
Follow the diagram that Defcon 1 shows. Buy new tools and supplies if necessary.
For supplies, you'll need new wires (two or three different colors, one being black for ground), a ring connector for the ground, butt connectors to connect the wires to the switch, a new switch, solder, plastic conduit and shrink tube. If you run the new wires through a new hole in the firewall, you'll need a proper sized grommet. You may be able to run your new wires through the existing conduit for part of the way. Use 1/4" plastic conduit for where the factory conduit doesn't reach.
For tools, You'll need a wire cutter/stripper, a soldering gun (buy a good one and it'll last many years), a heat gun or possibly a hair dryer to shrink the shrink tubing, and probably a drill. Butt connectors aren't evil. You can buy an assortment of connectors with a crimping tool for a few bucks.
If you aren't sure about your soldering skills, watch a couple UTUBE videos. It's real easy once you get the hang of it. Always remember to slide the shrink tube over the wire prior to soldering the connection. With a little practice, you can easily become a soldering pro. Just remember to get the wires hot enough so that the solder flows when you touch it to the wires. Use the soldering gun to heat the wires, not the solder.
Most home and professional mechanics will agree, solder and shrink tube connections are more secure than standard butt connectors. There are some styles of butt connectors designed for aircraft and marine use that are as secure as solder and shrink tube, but the solder/shrink tube connections are more practical for the average home mechanic.
When I use butt connectors to make connections like the ground or to the switch, I pull the supplied plastic off the connector and slide a piece of shrink tube over the wire. Then I crimp the butt connector in place and solder it. Slip the tube into place and heat it.
I don't think there's a more practical and secure way to do permanent automotive wiring.
Good Luck, L.M.