Every vehicle other than a school bus, motorcycle, motor-driven cycle or moped operated upon a highway within this state at any time from sunset to sunrise, or during fog, smoke, rain or other unfavorable atmospheric conditions, or at any other time when there is not sufficient light to render clearly discernible persons and vehicles on the highway at a distance of five hundred feet ahead, shall display lighted head lamps and illuminating devices as hereinafter respectively required for different classes of vehicles, subject to exceptions with respect to parked vehicles as provided for in subsection (c), section fifteen-c of this article. Every school bus, motorcycle, motor-driven cycle and moped shall display lighted head lamps at all times when upon the highway. Lighted lamps and other lighting devices that consist of multiple light-emitting diodes (LEDs) or other illuminating components that function as a single lighting unit are deemed to be functional so long as at least sixty-six percent of the LEDs or other illuminating components are functional: Provided, That the lighted lamps or lighting devices must still project sufficient illumination to satisfy all other requirements contained in this article.