How do daytime running lights work?
Basically, daytime running lights, or (DRL) as they may be listed, are your vehicle's low beam headlights that are on during daytime driving. By having them on they increase the visibility of your vehicle on the highway, much like when the manufacturer's added the third brake light to vehicles. They are triggered or turned on by a computer or module that uses a light sensor to detect the ambient (surrounding) daylight and will automatically illuminate to provide that added layer of safety.
Usually the lights will run at a lower power setting than when your headlights are on for night driving. They can also take the form of a line of LED lights which often looks like an eyebrow on the front of the car. They may also be your low beam headlights on normal power, fog lights run at lower power or special lights that function for this purpose specifically.
They were first installed on import vehicles used in other countries but have made their way to mainstream use in the United States and have been around for years. Canada made them mandatory in 1989. These lights are standard on many domestic, import, and US built and sold vehicles. They were also offered as an option once they were approved by the (NHTSA) National Highway Traffic Safety Administration in 1993.
These lights add a layer of safety especially during the dawn to dusk hours when traditional lights may be off. Many state highway organization require lights on in work areas as well as when traveling through tunnels. Though they could reduce the overall life of your vehicle's lights, I recommend them highly and personally use my standard lights as DRL everyday.
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