Thanks for the input fredjacksonsan.
Here's how I figured it out for those in a similar situation. I pulled the entire relay panel free, and then opened up the back. I could immediately see that there was a missing relay. Then I looked at the wire running to the horn and saw it was green/red stripe.
Sure enough the missing relay had the green/red wire. Plugged in a rely and "horn". Before I pulled the back of the panel off, I thought there were only 2 relays wired. So make sure to snap it open to get a good view.
Aloha.