If you can mark the wires and remove the harness, then lay it out on a piece of 4x8 plywood, and using nails in the board and a marker you mark where the wires come out of the harness, and then label the wires on the board. Then you can lay in the new wire and use twist ties to hold temporary till you get all the wires in place. Its also best not to just crimp on the connectors, The water will cause major problems later, Best is to use heat shrink tubing and solder everything then coat the connection with dielectric grease to keep moisture and sait etc out.
