Every motor vehicle shall be equipped with a signal lamp or signal device which is so constructed and located on the vehicle as to give a signal of intention to stop, which shall be red or yellow in color, which signal shall be plainly visible and understandable in normal sunlight and at night from a distance of one hundred feet to the rear but shall not project a glaring or dazzling light.
Iowa Code § 321.404
Referred to in §321.1, 321.234A, 321.404A, 456A.12, 805.8A(3)(t)
For applicable scheduled fine, see §805.8A, subsection 3