There's two horns. One hi-tone and one lo-tone. They are located in the bottom corners of the front bumper. There is an inspection panel inside each wheel arch that just about allows access. My lo-tone in the n/s/f bumper had packed up. I turned the adjuster screw on the horn about half a turn in and it now works fine. It may also be a corroded connection as they are prone to water ingress.