Michigan Compiled Laws, Chapter 257. Motor Vehicles § 257.1817

Sec. 17. (1) This section applies to school buses manufactured before October 1, 1990 that have not been retrofitted to meet the requirements of section 19.  1

(2) A school bus shall be equipped with signal lights mounted as high and widely spaced laterally as practicable that are capable of displaying to the front 2 overhead alternately flashing red lights located at the same level and to the rear 2 overhead alternately flashing red lights located at the same level. These lights shall have sufficient intensity to be visible from a distance of not less than 500 feet in normal sunlight.

(3) Overhead alternately flashing stoplights shall be operated by a manually operated switch and detached from any other instrument on the bus. A flashing light shall not be connected to the brakes or the service door on school buses manufactured before October 1, 1990. A 3-inch black area shall be provided around flasher lamps front and rear. Lamps indicating alternating flashing light operation shall be visible to the driver when in a normal seated position.

(4) Signal lights and stoplights under this section shall be in conformance with current United States department of transportation federal motor vehicle safety regulations found in 49 CFR part 571.