The loss of a headlight makes nighttime driving hazardous, and may even attract the unwanted attention of the local police. A burned-out taillight, stoplight or turn indicator lamp creates a hazard for other motorists because these lamps signal a vehicle’s directional intentions to other drivers. Bulbs that provide illumination for instrumentation are also important because they allow the driver to monitor the speedometer and other gauges. Even something as simple as a failed trunk light or dome light can create an inconvenience when operating a vehicle after dark.

So your job as a technician or repair shop owner is to help customers “see the light” when they need a replacement lamp or bulb.

Light Years of Evolution
Years ago, all headlights were sealed beams. So if your customer needs a replacement headlight for a 1980s vintage or older vehicle, there are only a few basic sizes of round and rectangular beams: Those for two headlight applications (6014 round high/low sealed beam and 6052 rectangular high/low-beam) and those for four headlight systems (4000 round low-beam, 4001 round high-beam, 4652 rectangular low-beam and 4651 rectangular high-beam).

Most of these older style sealed beams were originally standard incandescent lamps. In 1978, the federal government revised its headlight regulations to allow the use of “halogen” sealed beams. Halogen lamps are brighter and last longer than regu...