You'll have to trace the wires off switch to the bundle to see if there's a connector. I did that with my accessory switch and found the extra lead to use for my fishfinder. If it's bundled up and zip tied, it will be much easier to cut the zip ties to find it. Trust me! Then when finished, zip tie the bundle up again. A schematic won't show anything but maybe a connector available , but it won't show its specific location.
Also look in your owners manual package, mine had a schematic in there.