I have the opposite problem on my 76 FJ40. After an inadvertent short from ammeter wiring in dash while replacing a brake light switch, I toasted some wiring :-(( Now my horn wont stop honking!
I did find some heat damaged insulation on wires to ammeter and spliced in new connections. Everything else works, but had to disconnect the wires to horns. I looked at wires coming from horn switch on column and no siges of any heat damage. Previous owner had installed an alarm system, so wiring under dash is a rats nest. Could a faulty horn relay or wiring at the relay cause the horn to continuously honk? I am an electrical novice, but trying to figure this out!!!
1976 FJ40 chev v8