(a) Every motor vehicle, when operated upon any road, street or highway of the state, shall be equipped with a horn in good working order capable of emitting sound audible under normal conditions from a distance of not less than two hundred feet (200′), and it is unlawful, except as otherwise provided in this section, for any vehicle to be equipped with or for any person to use upon a vehicle any siren, exhaust, compression or spark plug whistle or for any person at any time to use a horn otherwise than as a reasonable warning or to make any unnecessary or unreasonably loud or harsh sound by means of a horn or other warning device.
(b) Every police, fire department and fire patrol vehicle, and every ambulance and emergency repair vehicle of public service companies used for emergency calls, shall be equipped with a bell, siren, or exhaust whistle of a type approved by the department, or local police authorities in incorporated cities or towns. Members of volunteer fire departments residing outside of incorporated communities may equip vehicles, to be used in fire patrol work, with warning devices of the type approved by the department or by the sheriff of the county in which the vehicles are to be operated.
(c)

(1) Members of regular or volunteer fire departments may equip their privately owned vehicles to be used in responding to a fire alarm or other emergency with warning devices approved by the local fire chief, upon written certification to the local sheriff or police chief that the person is a member of the department. In the event the warning devices are abused or used for other than their intended purpose by a member of the fire department, the local fire chief shall revoke the member’s privilege of using the warning devices and shall notify, in writing, the local sheriff or police chief of the revocation.
(2) Subdivision (c)(1) shall not apply to counties with populations of:

not less than

nor more than

83,300

83,400

85,725

85,825

143,900

144,000

250,000

300,000

400,000

–

according to the 1980 federal census or any subsequent federal census.

(d)

(1) The prohibition in subsection (a) does not apply to any privately-owned motor vehicle that is primarily operated for business purposes by any salesperson, service representative, employee, lessee, or duly authorized agent of an emergency equipment company; provided, that the vehicle is marked with the lettering required by subdivision (d)(3).
(2) Any person operating a motor vehicle pursuant to this subsection (d) shall carry a copy of the company’s business license or the person’s or owner of the company’s professional or occupational license, certification or registration issued by this state and appropriate identification issued by the owner of the company.
(3) Lettering shall be displayed on the left and right sides of the vehicle identifying the name of the company for which the vehicle is operated and on the front and rear of the vehicle designating it a “Demonstration Vehicle.” The lettering shall be painted or affixed on, or attached to, the vehicle in a permanent manner, and shall be at least three inches (3″) in size.
(4) Nothing in this subsection (d) imposes any duty or obligation on a manufacturer of motor vehicles used by or sold to emergency equipment companies to equip the audible warning devices allowed in this subsection (d) at the time of manufacture or sale.
(5) Nothing in this subsection (d) shall be construed to permit the operator of an emergency equipment company vehicle from operating any audible warning device authorized by this subsection (d) while the vehicle is on a public road, whether in motion or stationary.
(6) As used in this section, “emergency equipment company” or “company” means any entity licensed as required by this state to sell or repair bells, sirens, or exhaust, compression or spark plug whistles, or other audible warning devices or equipment designed for use on motor vehicles that are operated for authorized law enforcement, emergency response, or other public safety activities.
(e) A violation of this section is a Class C misdemeanor.