When I bought my boat in the year 2000 there was a rat's nest of engine wires, all heavily taped together. I never dared touch any of it other than occasionally cleaning a few plugs and the like. When it came time to pull the engine out of the boat a few years ago, I decided to unwrap the mess, trace each wire, get rid of unused wires and shorten all the others, and otherwise decipher, label and replace when necessary every last wire. It was a much simpler project than I expected, and very satisfying. Afterwards, one of the mechanics at my boatyard said he doesn't often see such clean engine wiring. Gotta credit Mainsail and his recommendations of tools and techniques.