just my two cents. . . . .
my (air)horn used to set off in the middle of the night when temperatures drop in the winter and wake the neigbourhood until the circuit breaker burned out a few times.
i tried to run the horn power by a line that was only powered when the engine was on but that resulted in ramdom horning while driving.
It was the airbag crimping in the cold that activated the build in hornswitch.
i dissassembled the airbag, and lead the hornswitch-wires to the console where i mounted a simple chrome doorbell switch for my horn next to the handbrake.
a lot cheaper than a new airbag and it works great.