Thanks so much for this great instructions. I used them to install a new horn in my 2018 (the original horn is truly pathetic) and found a way to do this without having to install additional wiring or open any additional compartments under the hood. Here's what I did;
1- Bought a Wolo Bad Boy horn for the install. These are available online or at Harbor Freight for about $30. Not the loudest aftermarket horn around but plenty loud enough for my purposes (and WAY louder than the original).
2- Once the wheel well liner was off, I disconnected the wiring to the original horn, per the instructions above (BTW, the original horn can be removed if you have a small 12mm wrench- you just need to reach up and feel around for the single bolt that attaches it, and then unbolt it).
3- There is a small inverted plastic well right below the horn area. I drilled a hole through that well from below, put a single washer over the bolt that comes with the Bad Boy horn, and inserted that bolt through the hole.
4- Attach the horn wires from the Leaf to the new horn (brown to positive, black to negative) . The connectors are the same size as on the old horn, so they fit perfectly.
5- Put 3 washers on the bolt so the horn will set level on the plastic well. Put the nut that comes with the bolt horn into the little metal connector flange on the horn, and then screw the bolt into the nut and tighten.
6- That's it! Now just follow the original instructions for re-attaching the wheel well liner and putting the wheel/tire back on.
Can't tell you how great it is to have a horn that actually gets people's attention. Once again, thank you for posting these instructions!