2026 GMC Sierra 1500 Electrical system Problems

“What component or system failed or malfunctioned, and is it available for inspection upon request? The truck has lost power unexpectedly while driving, and lately I've also noticed some lag when I accelerate. The truck is available to be inspected. How was your safety or the safety of others put at risk? The truck suddenly lost power while I was driving and told me to restart the vehicle. Losing power unexpectedly almost caused me to get stuck in an intersection and could have caused an accident in a busy shopping center. …”

“Three different times now (most recent: 10/22/2026), I have had my truck completely shut off when coming to a stop on the highway/interstate. I always have auto start/stop disabled when I drive. When it happens, a message shows on the dash that says press start button. No other codes or check engine light. Thankfully it has started every time, but this is obviously a serious safety concern. After the second time it happened, I had the dealer (Woodhouse Buick GMC Omaha) look at it on 9/14/2026, but they couldn't find anything since there were no codes. …”

“I had this truck as brand new for approximately 24 hours when it had a major failure. It had 450 miles on it at time of purchase, but was sold as new. While driving at 45MPH it had a check engine light, service power steering message, lost power steering, lane departure system failure, and reduced power amongst several other lights on the dash. I limped the truck into a gas station parking lot. After turning the truck off, it would not restart. I unhooked the battery for a minute and hooked it back up. The truck did restart with no messages or check engine light. …”

“5/08/2026: I stopped outside my garage. I then placed the truck in park and exited the vehicle while running. I went inside my garage and several minutes later, heard a crash. The truck had driven forward while unattended, and crashed into the corner of my garage, causing damage to both the building and the truck. Truck indicated it was still in park upon reentry. 5/11/2026 In a separate incident 3 days later, while driving at approximately 50mph, truck engaged in an automatic braking event with no discernible cause. Simply applied what felt like 100% braking for a split second, then released. …”

“6 month old, 9,000 miles 2026 Sierra 1500 with Duramax 3 liter suffered an engine control module failure 4 hours into a 12.5 hour drive home from family vacation. First a transmission service warning flashed, then an emissions system failure with a forced speed reduction warning. This happened with two children and a dog in the vehicle. OnStar did diagnotics and said I had to see a dealer. …”