David,
If you look at the diagram again, you will see the horn has two wires attached to it. One wire comes from power and enters the horn. Another wire is shown going to a horn button.
The power wire enters the horn and terminates on a vibrator that is insulated from ground. The second wire that goes up your column to the horn button completes that circuit and supplies ground when you depress the horn.
Does this make sense? That wire sticking out of the bottom of the column travels up to the steering wheel, and through combination of insulated little discs, springs and what-not, allow you to turn the wheel, yet be able to ground that circuit when you mash the button...toot toot!
I sure hope this is how it works!
Stuart
