Iowa Code § 321.395: Lamps on parked vehicles.

Whenever a vehicle is parked or stopped upon a roadway or shoulder adjacent to the roadway, outside of a business district whether attended or unattended during the times mentioned in section 321.384, such vehicle shall be equipped with one or more lamps which shall exhibit a white or amber light on the roadway side visible from a distance of five hundred feet to the front of such vehicle and a red light visible from a distance of five hundred feet to the rear, except that local authorities may provide by ordinance or resolution that no lights need be displayed upon any such vehicle when stopped or parked in accordance with local parking regulations upon a highway where there is sufficient light to reveal any person or object within a distance of five hundred feet upon such highway. Any lighted headlamps upon a parked vehicle shall be depressed or dimmed.