2003-2005 Mercury Grand Marquis Park Side Markers Lights Set Left Driver Right Passenger Pair Assembly

HID stands for "High Intensity Discharge". These bulbs use an electric arc rather than the glowing filament in a Halogen bulb. HID headlamp bulbs do not run on low-voltage DC current like a Halogen Bulb, so they require a ballast, which controls and regulates the flow of current. This ballast will require an ignitor to light the bulb. This is either integrated directly into the bulb or as a separate unit which is occasionally part of the ballast, similar to fluorescent bulbs in your home. In a vehicle, HID bulbs tend to be much more expensive to replace than a Halogen bulb.

Halo lights are lights arranged in a ring around the headlights themselves. You've probably seen them on some cars, such as BMWs, where they are the factory option. In some cases the effect is achieved with bulbs, while on other vehicles it's done with fiber optics. Halo Lights can be a popular upgrade to make your car or truck stand out at night. Please be aware that most of theHalo lights we sell typically have to be manually wired up to your existing wiring harness. This is because your stock vehicle did not have Halos, and there is no wiring pigtail for them on the factory harness.

You may well have to adjust the headlights after installation. If it's possible, when you take the old assembly out, you should match up the new adjusters with the old ones. Adjust the new light as close to that on the old units as you can. That way, any adjustments you have to make on the car once they are installed will be minimal. Our headlight assemblies have the same or improved adjusters as the stock units, and there are many videos on Youtube on how to adjust lighting. Check your owners manual too, since not all vehicles are adjusted the same way. Finally, when adjusting, make sure your car is level, with a full tank of gas.