California Code, Vehicle Code - VEH § 25805

Notwithstanding any other provision of this article, a forklift truck which is towed upon the highway at the end of a combination of vehicles shall at all times be equipped with at least one stop lamp mounted upon the rear of the vehicle and shall be equipped with lamp-type turn signals. Such vehicle shall, during the hours of darkness, be equipped with at least one taillamp and one red reflector mounted upon the rear of the vehicle and shall be equipped with clearance lamps if the vehicle is 80 or more inches in width.