Headlight Bulb Replacement: 2021 GMC Sierra 3500 HD AT4 6.6L V8 Turbo Diesel

This video shows you how to replace a headlight bulb in your 2021 GMC Sierra 3500 HD, your headlight bulb may also be known as a headlight low beam. Headlights grow dimmer by up to 20% over time and eventually burn out - for this reason, we recommend changing your headlights in pairs. Changing both headlight bulbs on your Sierra 3500 HD at the same time will allow both bulbs to have the same intensity and prevent the new headlight bulb from appearing brighter than the bulb on the opposite side.

In some GMCs, the highbeam is the same bulb as the headlight and it is possible for the highbeam to work, but the headlight be burnt out even if they are the same bulb (and vice versa). Some GMCs have high intensity discharge headlights, sometimes referred to as xenon lights. 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 Sierra 3500 HD has a HID headlight burnt out, it could be a burnt out bulb or failed headlight ballast.

The headlight bulb replacement cost for your Sierra 3500 HD varies depending on where you go to get your headlight replaced. GMC dealerships will tend to be pricier and parts retailers such as AutoZone will often replace it for free if you buy bulbs there. When you change the headlight on your Sierra 3500 HD, it is important to not touch the glass part of the bulb with your fingers because the oil from your fingertips will cause that part of the bulb to burn hotter, which significantly shortens the life of the bulb.