Update for anyone interested.
I spoke with Spartan and my chassis does not have a horn relay. The horns are activated by the SCM (Spartan Control Module). I tried a reset on the SCM per Spartan instructions. Horns still blowing. I talked with a Spartan tech and he gave me a trouble shooting procedure to determine if the problem was internal to the SCM. Ran that and according to my results the SCM is at fault. New SCM $1012.28.