[RICK LAKE]

Bliss I had the same problem. I also see in the picture and I think it's the speedo cable, wires rubbing on the top. Unscrew cable and get wires run below cable. If you can smooth out the loop in the cable than would help to and expend the life of it.
Easiest way to fix this is a razor knife and open up the wiring harness. You may want to remove the windshield and steer column from the car for easy way to repair this. Sound like a pain but all you have to do is flip the dash 90 degrees to repair. Work 1 wire at a time. Remove and splice in a new one. Solder the ends and seal them. Some of the better auto stores have bulk wire in different colors. Try and match gauge thickness and color if possible. Match the Gauge wire if nothing else. Larger the wire the more amps it has to carry. Trailer stores also have wiring in bulk, Like house or boat trailers. If not Electrical outlets. When done with the repair, leave the dash loose to see behind and run the car. You can do this by hand or with a infrared temp gun and watch and check for hot wires. They will be easy to touch. Run the car about 5-10 minutes if no smoke or hot wires show, put the car back togeather. I like wireties and use less tape. Weather will not hurt the wiring under the dash if it gets wet.
Volt gauge, very easy to do, The 2 main wires that would have gone back to the amp gauge now are connected together with large crimping connector or just replace the 2 wires, (which is better since you have the dash loose) and add new ends to where they go. For the gauge just add a wire split into the large wire. Everybody has a different way to do this, here's mine, Get a 1" piece of 16 gauge wire, match the color if possible. this tells you or a mechanic it's a power all the time line. I pull back just enough of the wire cover to patch the wire in. I use an awl to push though the wires and make a hole. Strip the match wire about 1" and run this through the hole and wrap it around the main wire. Nice spot of soldered for good contact. They sell liquid plastic wire sealer in electric at Lowes and homedepot. Put a couple of light coats on the connection. Tape over if you want too. Better than new.
Install gauge. Cut the pigtail to length and add eyelet to end of wire. Use the liquid seal or tape or swrink tubing to protect for wire rub, and kepts out weather from corriding the connector. The instructions tell you which terminal the line goes to. Next find a ground wire. They are black most of the time. You need a test light or ohm meter to check this. Once you find a good ground wire run a pigtail of black 16 gauge to the other side of the meter. Light explains itself and should just clip in. If it's a different socket than splice in the new one to the light feed. Take your time. There must be a couple of guys in the area that would help you with this. Normally a couple of beers and a steak will win over any good guy. NO driving after the beer. If you have a problem, stop and call, Will walk you through this. Rick L. 732-254-3536 Home after 7:00 pm est time. Good luck . Sorry a voltgauge and amp gauge are not wired the same. All the power of your electrical system go through the amp gauge. Over time the load and heat melt the insolator on the amp gauge and you get smoked. Voltage gauge just samples the amount of power your charging system and draws use and the number is whats left over with th car running. It's also a quick battery tester. Turn Ign switch to on and you can see the voltage of the battery.