I've had this wired up in the past but I forget how it was done and some things came apart. We have a simple 12v horn and relay. The relay is a KUMP 7D58-12. Here (https://i.stack.imgur.com/82O88.jpg) are some pictures of how I think it should be wired. I don't want to try anything before I have it checked so that's my question. The 12v is supplied from a 48v>12v converter already installed.
If I missed something in there that needs explained, let me know.