Wiring can be trouble for most, but have patience. If you separate the systems it's not that bad. Take some time and take notes of what wire color/size goes where. Remember that the main harness may have 25 wires in it, but each one usually breaks down to individual circuits. One ignition, stern light, oil pressure sensor, a few for trim pump, a main power feed, etc....again, take time, make your own drawings, compare factory schematic, mark wires with masking tape and pen. In short order you will have it figured out. Good luck.
