2013 Arizona Laws 28-981. Vehicle equipment; safety requirement
A. A person shall not drive or move on a highway a motor vehicle, tow truck, trailer, semitrailer or pole trailer or any combination of a motor vehicle, tow truck, trailer, semitrailer or pole trailer unless:
1. The equipment on the vehicle is in good working order and adjustment as required in this chapter.
2. The vehicle is in a safe mechanical condition that does not endanger the driver or other occupant or a person on the highway.
B. The provisions of this article with respect to equipment on vehicles do not apply to trailers used solely in the operation of a farm for the transportation of unprocessed fiber products on the farm or from a farm to a cotton gin, road machinery, road rollers, farm tractors or implements of husbandry when the implement is being incidentally operated or moved on a highway whether as a trailer or self-propelled unit. For the purposes of this subsection, “incidentally operated or moved on a highway” means travel between a farm and another part of the same farm, from one farm to another farm or between a farm and a place of repair, supply or storage.