(1) The addition of a lamp, reflective device or other motor vehicle equipment must not impair the effectiveness of lighting equipment required by 49 C.F.R. Part 571.108 or chapter 46.37 RCW.

(a) If a vehicle is in motion on a public roadway, the vehicle must not:

(i) Display aftermarket neon lighting devices.

(ii) Combine any type of letter, number, sign, symbol or combination thereof with an eye level brake light meeting the standards of 49 C.F.R. Part 571.108 (FMVSS 108). No function other than red reflex reflectors will be combined in eye level brake lights.

(iii) Have a lighted or electrically/mechanically powered sign or message board enabling change or movement of any displayed message to be displayed or affixed to the vehicle. Except:

(A) Vehicles that are used in conjunction with officially sanctioned or sponsored motor vehicle traffic control or movement may display lighted or electrically powered signs to assist in the efficient control of traffic movement on public roadways. The signs must be designed, worded, and located to limit misinterpretation and confusion by the motoring public.

(B) Electric signs may be unitized to identify taxicabs and the destinations of mass transportation vehicles. These signs must not contain any commercial or personal message and must be designed, worded, and located so that it is clearly differentiated from other required motor vehicle lights.

(b) If a vehicle is not in motion and parked on private property, the vehicle may use aftermarket lighting except as outlined under RCW 46.37.180.

(c) This section is not intended to prohibit a scrolling sign provided that the scrolling sign must:

(i) Be powered by an external source or in a manner which does not cause the required equipment on the vehicle to be out of compliance with 49 C.F.R. Part 571, chapter 46.37 RCW or Title 204 WAC.

(ii) Not be lit.

(iii) Not have continual motion.

(2) Pursuant to Title 49 C.F.R. Part 571.108, the addition of an aftermarket style ornament or other feature such as tinted plastic glass covers, a grille or slotted covers must not be placed in front of the headlamp lens, or in front of any other lighting devices installed on motor vehicles which impair the effectiveness of lighting equipment required under 49 C.F.R. Part 571.108 (FMVSS 108) or chapter 46.37 RCW. Except:

(a) Clear aftermarket headlamp covers.

(b) Headlamp wipers may be used in front of the lens provided that the headlamp system is designed to conform to all applicable photometric requirements in 49 C.F.R. Part 571.108 (FMVSS 108) with the wiper stopped in any position in front of the lens.

(c) A bike rack may be installed on the front of a municipal transit vehicle (as defined under RCW 46.04.355) provided that even with the bike rack installed, loaded or unloaded with bicycles, the headlight system still conforms with all applicable photometric requirements in 49 C.F.R. Part 571.108 (FMVSS 108).

(3) Red emergency lights are prohibited on any vehicle other than an authorized emergency vehicle, a law enforcement vehicle, an emergency tow truck as defined in WAC 204-21-020(8), school buses, and private carrier buses.

(4) Blue lights are prohibited on any vehicle other than a law enforcement vehicle as defined in WAC 204-21-020.

(5) Flashing white lights are prohibited on any vehicle other than authorized emergency vehicles, law enforcement vehicles, school buses, and emergency tow trucks as defined in WAC 204-21-020.