2025 GMC Hummer EV Pickup Problems

While traveling with my wife and two toddlers over the July 4th holiday weekend, the 12 volt battery on my 2025 GMC Hummer EV failed completely at approximately 7,500 miles and five months of ownership. The vehicle would not accept a jump start and was disabled where it sat, stranding my family. AAA installed a replacement 12 volt battery roadside at a cost of $600. Following the battery replacement, a Service High Voltage System warning appeared on the dash and remained on, and the air conditioning system stopped functioning entirely. This occurred in Southern California summer heat with two small children in the vehicle. The HVAC loss and the high voltage system warning persisted for weeks. I brought the vehicle to a GMC dealership on July 15, 2026, repair order 978148, reporting the high voltage warning, the inoperative AC, and the battery failure. The dealership held the vehicle 7 days and performed no diagnosis. On July 26 I performed a 12 volt battery disconnect and reset myself, after which the warning cleared and the AC returned. No root cause has ever been diagnosed. The condition may recur. I am filing this because a sudden 12 volt system failure on this platform disables the entire vehicle, including a no-jump condition, and in my case produced a high voltage system warning and total HVAC loss. A 12 volt failure that strands a vehicle in traffic or disables climate control in extreme heat with children aboard is a safety issue, and NHTSA's complaint database already contains other electrical system complaints on this model year. The root cause of my failure remains undiagnosed by GM or its dealer.

While traveling with my wife and two toddlers over the July 4th holiday weekend, the 12 volt battery on my 2025 GMC Hummer EV failed completely at approximately 7,500 miles and five months of ownership. The vehicle would not accept a jump start and was disabled where it sat, stranding my family. AAA installed a replacement 12 volt battery roadside at a cost of $600. Following the battery replacement, a Service High Voltage System warning appeared on the dash and remained on, and the air conditioning system stopped functioning entirely. This occurred in Southern California summer heat with two small children in the vehicle. The HVAC loss and the high voltage system warning persisted for weeks. I brought the vehicle to a GMC dealership on July 15, 2026, repair order 978148, reporting the high voltage warning, the inoperative AC, and the battery failure. The dealership held the vehicle 7 days and performed no diagnosis. On July 26 I performed a 12 volt battery disconnect and reset myself, after which the warning cleared and the AC returned. No root cause has ever been diagnosed. The condition may recur. I am filing this because a sudden 12 volt system failure on this platform disables the entire vehicle, including a no-jump condition, and in my case produced a high voltage system warning and total HVAC loss. A 12 volt failure that strands a vehicle in traffic or disables climate control in extreme heat with children aboard is a safety issue, and NHTSA's complaint database already contains other electrical system complaints on this model year. The root cause of my failure remains undiagnosed by GM or its dealer.

When it rains, within 24 hours, the windows do not automatically move down enough to open the door on command of pulling the door handle. This disallows the ability to close the door back if the door is open, barely underneath the lip of the sky panels. Because of this power loss, the mirrors do not open, the door locks do not work, and the windows do not work. To be able to re-close the doors, the sky panels must be removed and either left off or replaced. Essentially rain leaks into the body where wiring that controls door locks, door windows, causing electrical failure of this circuit only. After some hours of time without intervention function, restores, presumably due to drying out of wet parts.

I was driving down the street and suddenly lost all motive Power, vehicle became difficult to control. I have a video. The car also made a grinding feeling and very loud whining noise