Xenon headlights have a ballast to ignite the high voltage xenon lights when they turn on that can remain energized even if the lights are turned off. Be sure to disconnect the headlight assembly or battery before attempting to replace it. If your GL450 has a HID headlight burnt out, it could be a burnt out bulb or failed headlight ballast. If you use Xenon in place of halogen, you might replace the bulbs once for every time another person might replace halogen lights two or three times. This also helps you save money in the long run. Xenon Headlight Cons 1. High Cost. While they are longer-lasting than the halogen light, you are going to pay for it upfront. Xenon headlights have a ballast to ignite the high voltage xenon lights when they turn on that can remain energized even if the lights are turned off. Be sure to disconnect the headlight assembly or battery before attempting to replace it. If your 6 has a HID headlight burnt out, it could be a burnt out bulb or failed headlight ballast. How To: Replace the burned out headlights in your car How To: Repair auto headlights with a 3M Headlight Lens Restoration System How To: Fix the lamp out module on a 1996 Ford Explorer if your headlights are broken How To: Replace the headlights on a 99-04 Mustang How To: Replace a headlight in a Cadillac Xenon headlights have a ballast to ignite the high voltage xenon lights when they turn on that can remain energized even if the lights are turned off. Be sure to disconnect the headlight assembly or battery before attempting to replace it. If your Sorento has a HID headlight burnt out, it could be a burnt out bulb or failed headlight ballast. That will take you to the instructions involved in getting the headlights off. If you install the "aftermarket" rebased hid bulbs and ballasts kit I think you will be disappointed with the light output. The stock projectors do not emit the brighter xenon light very well. And you get lots of upward glare to oncoming drivers. Good luck. In this tutorial, I demonstrate how to replace a headlight bulb in a BMW 5 Series using simple and easy steps. Whether you're looking to upgrade your existin Features BentleyPublishers' MINI Cooper 2007-2011 Repair Manual (ER56, R55, R57) - http://www.bentleypublishers.com/c/BM13How to replace the Xenon headlight 9CJe.