625 ILCS 5/12-805
Each school bus purchased as a new vehicle after December 31, 1975 shall be equipped with an 8-lamp flashing signal system. Until December 31, 1978, all other school buses shall be equipped with either a 4-lamp or an 8-lamp flashing signal system. After December 31, 1978, all school buses shall be equipped with an 8-lamp flashing signal system.
A 4-lamp flashing signal system shall have 2 alternately flashing red lamps mounted as high and as widely spaced laterally on the same level as practicable at the front of the school bus and 2 such lamps mounted in the same manner at the rear.
An 8-lamp flashing signal system shall have, in addition to a 4-lamp system, 4 alternately flashing amber lamps. Each amber lamp shall be mounted next to a red lamp and at the same level but closer to the centerline of the school bus.
Each signal lamp shall be a sealed beam at least 5 1/2 inches in diameter and shall have sufficient intensity to be visible at 500 feet in normal sunlight. Both the 4-lamp and 8-lamp system shall be actuated only by means of a manual switch. There shall be a device for indicating to the driver that the system is operating properly or is inoperative.
A school bus may also be equipped with alternately flashing head lamps, which may be operated in conjunction with the 8-lamp flashing signal system.
625 ILCS 5/12-805