(A) 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 200 feet, but no horn or other warning device shall emit an unreasonably loud or harsh sound, or a 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.
(B) 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 division. Any authorized emergency vehicle, defined in § 70.01 or a vehicle operated by a fire chief, deputy fire chief, assistant fire chief, or the director or coordinator of a municipal or county emergency services and disaster agency, may be equipped with a siren, whistle, or bell capable of emitting sound audible under normal conditions from a distance of not less than 500 feet, but the siren, whistle, or bell 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 either of which events the driver of the vehicle shall sound the siren, whistle, or bell when necessary to warn pedestrians and other drivers of his approach.
(ILCS Ch. 625, Act 5, § 12-601) Penalty, see § 70.99