High Beam (Brights) Change: 2026 GMC Sierra 3500 HD AT4 6.6L V8 Turbo Diesel

This video shows you how to change the highbeams, which are also known as brights or headlight high beam bulbs, in your 2026 GMC Sierra 3500 HD. High beam lights can also be commonly referred to as a full beam whereas your headlights may be called the low beams. The high beam symbol in the dashboard on a 2026 GMC Sierra 3500 HD is typically represented as a blue headlight icon with beams pointing outward. In some GMCs your headlight and high beams are the same bulb – it is possible for the headlight portion of the bulb to burn out and for the highbeams to continue to function properly and vice versa. Replacing the bulb will restore functionality to both high and low beam functions. Highbeam bulbs grow dimmer by over 20% over time, therefore we recommend changing both bulbs on your Sierra 3500 HD at the same time, even if only one is burnt out - this will allow both high beam bulbs to have the same brightness on each side.

Be careful not to touch the glass part of the new highbeam bulb with your finger when changing it on your Sierra 3500 HD. Touching the new highbeam bulb will cause the bulb to burn out quicker. If you accidentally touch the glass part, wipe it off with rubbing alcohol before inserting it into your Sierra 3500 HD.