Idaho Statutes Title 49. Motor Vehicles § 49-956. Horns and warning devices

(1) Every motor vehicle when operated upon a highway shall 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, but no horn or other warning device shall emit an unreasonably loud or harsh sound or whistle. The driver of a motor vehicle shall when reasonably necessary to insure safe operation give audible warning with his horn, but shall not otherwise use the horn when upon a highway.

(2) No vehicle shall be equipped with nor shall any person use upon a vehicle any siren, whistle, or bell, except as otherwise permitted in this section.

(3) It is permissible, but not required for any vehicle to be equipped with a theft alarm signal device, so arranged that it cannot be used by the driver as an ordinary warning signal.

(4) Any authorized emergency vehicle may be equipped with a siren, whistle, or bell, capable of emitting sound audible under normal conditions from a distance of not less than five hundred (500) feet and of a type approved by the director, but the siren shall not be used except when the vehicle is operated in response to an emergency call or in the immediate pursuit of an actual or suspected violator of the law, in which the latter events the driver of the vehicle shall sound the siren when reasonably necessary to warn pedestrians and other drivers of the approach.