Wisconsin Statutes Vehicles (Ch. 340 to 351) § 347.145. Deceleration warning lights for motorcycles, motor bicycles, mopeds or motor buses

(1) A motorcycle, motor bicycle or moped may be equipped with and use a system in which an amber light which pulses in a controlled fashion at a rate which varies exponentially with deceleration is center mounted on the rear of the vehicle.

(2) A motor bus may be equipped with amber lights that shine with a steady beam or that pulse during deceleration, braking, or standing and idling. The lights shall be mounted symmetrically with respect to the vertical center line of the motor bus in a horizontal alignment on the rear of the motor bus. The lights may be mounted no higher than the lower edge of the rear window, or no higher than 72 inches if the motor bus does not have a rear window.