Up until 1990, the standard headlight assembly contained only incandescent sources, mostly separate, to create all desired functions. Whether the functions were created by sealed beam lamps or bulb, reflector, and optic assemblies, they all behaved in a similar manner. The light pattern was static and defined mainly by the reflector and optics. Standard supported lighting modes were high beam, low beam, turn signal, position, and fog lights. For many decades, these features provided only the basic light distribution needed to drive safely in most conditions...
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