Keystone/Dutchmen use a standardized wire identification scheme but I have not been able to find a wiring "diagram" as such for our Kodiak Ultra Lite so I might assume that the same goes for your trailer. I'm attaching the document I found that at least provides some information about wiring in Keystone/Dutchmen trailers. If you can identify the wires, they should have a numerical id printed on them, the attached document may assist you in determining what is causing the problem. Hope it helps.
As to a manual the only thing we got was generic the covers all of the their trailers and does not address any model specifically. You may have to go to each manufacturer website and download a manual for each item.
I agree with Persistent that pictures would help identify the problem. As a last resort taking the trailer to a Keystone/Dutchmen dealer might be the only solution but can cost some big bucks
to have them diagnose and fix the issue. Overheated wires are VERY dangerous and easily lead to fires as you have indicated. Get this issue fixed before getting out on the road. Keep asking questions as other owners here are always helpful.