For 1990-2009 cars only
When you depress the horn switch, the coil side of the horn relay is grounded. The relay is energized, the switch side of the relay closes, and the battery voltage is applied to the horns.
When you depress the horn switch, the coil side of the horn relay is grounded. The relay is energized, the switch side of the relay closes, and the battery voltage is applied to the horns.