What the diagram fails to show and studying it will reveal, is that it is a copy of the 1966 and prior vehicles. The relays and other wiring use the horn relay as a
primary junction and their connections have nothing to do with the horn function, Note the large red wire from the alternator. This wire is hot at all times so If it was tied to the horn it would honk constantly.
Here is a picture that better illustrates the issue. Note that the two terminals on the right end of the relay are separated from the horn terminals as I stated above.
