Wire in a 7 pin trailer hookup from scratch

[JellyBeanDriver]

You might want to get an isolator down the road. Especially for the parking lights, adding more load to the already thin gauge factory wiring can cause problems like overheating at the light switch connector.

Just went through this on an 86' C30. Replaced a bunch of burned wiring from a trailer short. Got much of what I needed from donor vehicles at the junkyard and a lot of those showed overheated parking light wiring at the light switch connector for those trucks that had trailer hookups. Many also had larger fuses installed in the fuse boxes and the wiring at the fuse box showed overheating damage.