It sounds as if your horns have power to them and your horn button is working, otherwise nothing would happen, but yours made some noise. The problem then is the horns them self, here is how they work. when power is applied to the horn through the horn button, the power passes through a closed electrical contact and then to a coil picking the coil up. When the coil picks up it mechanically moves the horn diaphragm and at the same time the electrical contact opens circuit causing the coil to drop out, when the coil drops out the contact closes again and the cycle repeats itself over and over very quickly. The result is the sound of the horn for as long as you apply the horn button. If the electrical contact is dirty and not closing properly the horns will not sound, if the contact does not open mechanically you may hear a slight noise and then nothing but the electrical circuit is energized and damage to any of it's components could happen.
Remove a horn and take the horn cover off and inspect the electrical contact and make sure they are closed and dirt and rust free could spray with an electrical cleaner), then with your hand squeeze the flat rectangular pole piece that is laminated down toward the electrical coil, watch the electrical contact as you depress the pole piece you should be able to see it just open. Most of the time the problem lies with dirt and loose rust around the electrical contact causing it not to close, or around the pole piece preventing it from moving fully. You can ignore the one other electrical device it is a capacitor soldered across the contact to eliminate arcing when the contacts open. You will be able to see adjustments that can be moved slightly (1/16 of a turn) adjusting the point the contacts open and close, and these adjustments also effect the horn tone and volume, get the horn to work first then adjust if necessary.
If your going to take the contact apart to clean make sure it is closed and opens properly before trying electrically.
