Unplug your horn wire out under the hood.
Then get in the Jeep and take the horn button off and turn it a 1/4 turn to the left. re-install and when it stops turning, push down and turn it a little more. The it will pop back up into the proper slot.
I installed a grant wheel in mine as well, and was having the same trouble. Figured out that I didn't have the horn button on correctly.
'87 YJ, 4.2L built and bored, 8" of lift, 8.8 rear, AX15/NP 231J, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...