Maybe try pulling the right fuse for starters.....rule of thumb,in most cases, always check fuse first,or in my case,walk around truck 10 times scratching head sweating out last nights hydraulic sandwiches.
Take the plastic cover off of the steering column. Carefully inspect the wires where they enter the shift handle. They can break or wear through the insulation there. Either fix the wires or replace the shift handle.
I ventured into this idea once. Repairing that lead coming out of the stalk would require great skill and patience. Those wires are tiny and removing the wrapping to expose the wires without damaging them further is difficult as well. If you want to "repair" it without replacing the shifter it can be done in some cases simply by re-sealing the bundle provided the location of the damage is not right at the point the wiring enters the shifter. usually it's further out because it rubs on the shift tube where the wire is draped over it. I have noticed over the years that the chaffing typically damages one wire only exposing the strand and not breaking it. It is possible to slide a piece of shrink tube onto it and seal it up... you could also simply tightly wrap a piece of electrical tape over the damage and what I like to do even when replacing is to take some 1/4" diameter convoluted tubing and install that over the wire for added chafe resistance. You can source the tubing at many auto parts stores, Home Depot or Lowes and of course the Internet provides many options as well, here is one: