CORRECTION CHARLES!! the horn fuse supplies power to your horn, rear tail lights, and your shifter mechanism if you have an automatic. basically, you car, if automatic, is designed with a brake shift interlock, preventing you from shifting the car out of gear without hitting the brakes simultaneously, hence, when in park, you need to hit the brake to pull your transmission out of park. you'll notice this feature if you idle your car in park and pump on the brake, you'll hear a nice clicking mechanism in your console. this is an electronically controlled mechanism that just so happens to be connected in line to your horn fuse. shitty design, but hey, it's mazda!
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