1. Remove the front bumper cover (or at least part of it): This usually involves removing several screws and clips that hold the bumper cover in place. Consult your owner's manual or a repair manual for your specific Blazer model for precise instructions. This step is necessary to get access to the horn.
2. Locate the horn itself: Once the bumper cover is partially or fully removed, the horn should be visible. It's usually a relatively large, cylindrical device, often mounted behind the bumper cover near the center. There might be two horns.
Without removing part of the bumper, you won't be able to access the horn. Remember to disconnect the battery's negative terminal before working on any electrical components, including the horn.