The goal of a new wire is to replace an old one that has a lot of corrosion. If you see a copper wire that is dark and dull brown, that's because it's corroded. Solder will not adhere to it no matter how well you shine up the strands. For that reason you have to cut it back far enough to expose nice shiny copper, and splice it there.
If the original attaching point is rusty, you can drill a new hole, grind the rust or paint off, then run in a new self-tapping screw to attach a new ground wire. How you do it and where you splice it depends on how close you can get to clean and solid material to attach to. If you're splicing a new wire to a part of the old wire, slide the strands together, (don't twist them like we do with wire nuts for house wiring), solder them, then slide on a piece of heat-shrink tubing to seal the connection. Don't use electrical tape because it will unravel into a gooey mess on a hot day. Auto parts stores have heat-shrink tubing with hot-melt glue inside to seal splices that will be exposed to moisture.
At the light sockets, I'd look for the ground wire and attach the new wire to it. As long as the break is before that point, all the other lights will have their ground wires spliced together, so your new wire will take care of all of them. The exception would be if a different ground wire was used on each side of the truck. If that's the case, you'll only have working lights on one side, and you'll have to do the same repair to the other side.
Wednesday, May 14th, 2014 AT 5:42 PM