Additional lighting equipment.

(1) Any motor vehicle may be equipped with not more than two side cowl or fender lamps which shall emit an amber or white light without glare.

(2) Any motor vehicle may be equipped with not more than one running-board courtesy lamp on each side thereof which shall emit a white or amber light without glare.

(3) Any motor vehicle may be equipped with one or more backup lamps either separately or in combination with other lamps, but any such backup lamp or lamps shall not be lighted when the motor vehicle is in forward motion.

(4) Any vehicle may be equipped with one or more side marker lamps, and any such lamp may be flashed in conjunction with turn or vehicular hazard warning signals. Side marker lamps located toward the front of a vehicle shall be amber, and side marker lamps located toward the rear shall be red.

(5) Any vehicle eighty inches or more in over-all width, if not otherwise required by RCW 46.37.090 , may be equipped with not more than three identification lamps showing to the front which shall emit an amber light without glare and not more than three identification lamps showing to the rear which shall emit a red light without glare. Such lamps shall be mounted as specified in RCW 46.37.090 (7).

(6)(a) Every motor vehicle, trailer, semitrailer, truck tractor, and pole trailer used in the state of Washington may be equipped with an auxiliary lighting system consisting of:

(i) One green light to be activated when the accelerator of the motor vehicle is depressed;

(ii) Not more than two amber lights to be activated when the motor vehicle is moving forward, or standing and idling, but is not under the power of the engine.

(b) Such auxiliary system shall not interfere with the operation of vehicle stop lamps or turn signals, as required by RCW 46.37.070 . Such system, however, may operate in conjunction with such stop lamps or turn signals.

(c) Only one color of the system may be illuminated at any one time, and at all times either the green light, or amber light or lights shall be illuminated when the stop lamps of the vehicle are not illuminated.

(d) The green light, and the amber light or lights, when illuminated shall be plainly visible at a distance of one thousand feet to the rear.

(e) Only one such system may be mounted on a motor vehicle, trailer, semitrailer, truck tractor, or pole trailer; and such system shall be rear mounted in a horizontal fashion, at a height of not more than seventy-two inches, nor less than twenty inches, as provided by RCW 46.37.050

(f) On a combination of vehicles, only the lights of the rearmost vehicle need actually be seen and distinguished as provided in subparagraph (d) of this subsection.