Have you checked the famous plug on these trucks that melts and burns out all the time? In the picture above, the yellow line that says "battery" should have two yellow wires on it. These are your hot all the time battery wires. If you follow these wires back over the valve cover, on the pass side inner fender you should run across a main wiring plug. These two yellow feed wires go through this plug along with some smaller wires, but this plug is way too small to do the job, and it usually melts. If yours is melted, you might need to cut these two large yellow wires out of it, and hook them together, bypassing the plug. I crimped 4 ring connectors on the yellow wires after I cut them out of the melted plug, and then used bolts to bolt them together. This is handy in case you have to do some work and need to disconnect the wiring(like replacing the valve cover gasket)