Replacing a body harness (or engine harness for that matter) is a difficult task. I think the truck has like 3 different harnesses, don't quote me on that. Lots to take apart. It is absolutely doable if one has the gumption. If you can locate the damaged wire (pin location, color, etc.) using a test light or what ever you choose, you can fix it at the damaged area, or cut, strip, and run a new wire from "A-B" to effectively jump the broken wire. Electrical problems that occur when the vehicle is jarred (IE hitting a bump) are often caused by loose grounds or connections. I would recommend inspecting all the connections, including ground locations, fuses, module, and harness connectors. Dirt and corrosion could be an issue is these areas. Electrical problems are often times hard to track down, but they can ALL be tracked down with a little determination and know how.