The horns will operate anytime the horn switch is pressed. The horns will also operate when the following systems are enacted:

Battery voltage is applied at all times to the horn relay thought circuit 740. When the horn switch is closed, ground from the steering wheel travels through circuit 28 and energizes the horn relay. Note: circuit 1450 also provides a redundant ground to the steering wheel. The horn relay can also be energized by the BCM grounding circuit 28. When the horn relay is energized, the switch in the horn relay closes. This action applies battery voltage to the horns through circuit 29, causing the horns to sound. The horns are connected to ground through circuit 1250.