How to automate continuity tests on harnesses with up to 200 connections
So you definitely need to connect all wires to connectors, some manual labor is required. But other than that it's a relatively simple board design project.
You would probably need something like a matrix of switches to address each wire, then apply voltage on one end and scan the other end. You would get a table matching both ends. Everything should be controlled by a microcontroller, or maybe by a PC, whatever is easy for you to code.
I think, that you should not do it by yourself. Find a contractor that is capable, they can do it quicker and cheaper then you will.