Ariz. Rev. Stat. § 28-939
A. A motor vehicle may be equipped and if required under this article shall be equipped with the following:
B. A stop lamp shall be plainly visible and understandable from a distance of one hundred feet to the rear both during normal sunlight and at nighttime. A signal lamp or lamps indicating the intention to turn shall be visible and understandable during daytime and nighttime from a distance of one hundred feet both to the front and rear. If a vehicle is equipped with a stop lamp, tail lamp or other signal lamp, each lamp shall: