A motor vehicle, when operated upon a highway, must be equipped with a horn in good working order and capable of emitting sound audible under normal conditions from a distance of not less than two hundred (200) feet. However, a horn or other warning device may not emit an unreasonably loud or harsh sound or a whistle.
IC 9-19-5-1
Pre-1991 Recodification Citation: 9-8-6-35(a) part.