I'm afraid you have a nightmare there. To try and figure out where all that stuffs is going ahead of time is going to be quite a challenge...not sure it's worth it if you don't really need to.
What I have done in similar situations is CAREFULLY pull the burnt section apart, one wire at a time, trying for all your worth not to break any of the wires. Use a razor blade to cut the burnt insulation if you need, to allow doing this. I've been pretty lucky doing this with worst case only having to figure out a couple of wires. Once separated just splice in new sections of wire as necessary. The one or two wires you might break will be easy to figure out with a full systems check. SOMETHING's not going to work.... FWIW
1997 37' HR Endeavor, 275hp Cat, Freightliner
03 CR-V Blue Ox, Ready Brake