For 1990-2009 cars

Battery voltage is applied at all times to the horn relay at terminal 86 and terminal 30. The horn relay is energized when the horn switch is closed to the ground. The switch in the horn relay closes, applying battery voltage to the horns through CKT 29. This action activates the horns.

On vehicles equipped with UA6 theft deterrent system, the horns will turn on when the theft deterrent system is activated. If the vehicle is tampered with, the switch in the body control module closes, sending a ground signal through CKT 28 to the horn relay. This action closes the switch in the horn relay, sending voltage through CKT 29 to the horns. This action activates the horns.