Having your exterior lights randomly stop working is never a fun experience—especially when you’re relying on a heavy-duty rig after dark. If you own a 2024–2026 Chevrolet Silverado HD or a GMC Sierra HD, I want to give you a quick heads-up on a known issue that might save you some diagnostic headaches at the dealership.
General Motors has recently released technical guidance explaining why your headlamps, Daytime Running Lamps (DRL), parking lamps, or turn signals might be intermittently failing.
If you’ve experienced this, you might have noticed that the lighting sometimes completely recovers after you simply turn the ignition off and cycle the truck back on. While that quick reboot might get you safely down the road, it’s only a temporary band-aid. Here is what is actually going on behind the grille.
The Culprit: The Multi-Purpose LED Driver
Digging into GM’s technical documents, this intermittent lighting failure usually points to an internal failure of the Multi-purpose LED Driver (MLD). Think of the MLD as the brain that controls the various lighting functions inside your headlamp assembly.
If your dealership traces the problem to a failed MLD, they will need to replace the module. The repair involves pulling the entire headlamp assembly out of the truck to swap the driver. To prevent damage, technicians are specifically instructed to carefully hand-tighten the mounting screws so they don’t strip the housing, and they must ensure the weather seal is perfectly seated.
If the new MLD doesn’t fix the issue during their post-install check, they will have to replace the entire headlamp assembly. (Pro Tip: If you need to point your service advisor in the right direction, tell them to reference Bulletin #26-NA-002 for the fix and part numbers).
A Special Note for 2025 Sierra HD Owners
Before you or your tech assume the MLD is to blame, there is one major exception you need to know about. A known soldering defect right from the factory can cause these exact same lighting functions to drop out on certain 2025 Sierra 2500HD and 3500HD models.
To verify this, technicians will check a separate bulletin (Bulletin #25-NA-337) and read the Julian date and part number stamped right on your headlamp. If your Sierra has one of these specific defective lamps, replacing the MLD won’t do a thing—the affected headlamp assembly must be completely replaced.
Are your HD truck’s lights acting up? Jump into our 2020-2026 Silverado HD & Sierra HD Forums and let the community know if your dealer swapped the MLD or the whole housing so other owners know exactly what to expect.
Zane Merva is the Executive Editor of GM-Trucks.com and the President of the New England Motor Press Association (NEMPA). A veteran automotive journalist with over 26 years of experience, Zane is a designated ‘Car Talk’ Expert and has been a contributor to The Boston Globe. He possesses a unique evaluative perspective, having road-tested more than 2,000 vehicles across every major manufacturer. While he is a recognized authority on General Motors truck platforms—including the Silverado, Sierra, and Colorado—his expertise is grounded in decades of deep competitive analysis that few in the industry can match. His commentary has been featured by major OEMs and media outlets, including Hyundai and PR Newswire