Where is the horn relay located on a 2010 Mazda 3?

The horn relay on a 2010 Mazda 3 is located in the engine compartment fuse box. To access it, open the hood and find the fuse box near the battery. The relay is typically labeled, so you can identify it by checking the diagram on the fuse box cover. If you're having issues with the horn, checking this relay is a good starting point.