The HORN fuse in the underhood fuse block applies voltage at all times to the horn relay. Depressing the horn switch closes the horn switch contacts. Closing the horn switch contacts provides a ground to the coil of the horn relay. Grounding the coil of the relay energizes the relay. Energizing the relay and closing the contacts applies the battery voltage directly to the right side horn and the left side horn. Since the right side horn grounds at G100 and the left side horn grounds at G101, the horn will sound as long as you press the horn switch.

The Body Control Module (BCM) can also provide a ground for the horn. When the horn relay control in the BCM closes, the BCM provides a ground for the horn relay coil. This closes the relay contacts and allows battery voltage to be applied to the horns.