I read some of your earlier posts.
Looks like you have a V8 with automatic transmission and a (new?) Speedway wiring harness. Recently, you have been working on the brake light. The truck was was running fine until you wired up the brake light and now you have burnt wires. Most drivers put their foot on the brake when starting the vehicle so I suspect the brake light is shorted out.
Does that make sense?
Thanks! Yep, I follow the logic that you have laid out, but I had not even gotten to hooking up the brake lights to anything with power just yet. I was just waiting for the new brake light switch to show up so I could go to that next.
All that was hooked up was the basic wire components to the engine, and a tach. Everything had been fine otherwise.