Have you started with the very basic stuff yet? Like be sure terminals on the battery are clean and seated properly. I have always said a simple test light is sometimes your first and best tool for these issues. I have one in all my trucks. start with checking the battery. Then give yourself a known good ground like using a jump lead direct to the battery and start tracing wires. Bet it's a simple solution. Just google wiring diagrams for your truck they are all over the internet.
Patches are for Pirates and pants, not a bulkhead and chassis!