625 ILCS 5/12-804

Other vehicles - Color, stop signal arm and identification. No vehicle other than a school bus shall be identified with the sign "SCHOOL BUS", shall be equipped with a stop signal arm, shall be equipped with a strobe lamp or shall be equipped with a warning lamp system as described in Section 12-805 of this Act. No commuter van or bus other than a school bus shall be painted national school bus glossy yellow or a color that closely resembles national school bus glossy yellow.