2025 GMC Hummer EV Problems: 3 Known Issues

On the 2022-2025 GMC Hummer EV, one of the most frequently reported real-world failures on the Hummer EV Pickup is parasitic drain on the 12V auxiliary battery, which leaves an otherwise fully charged truck totally unresponsive - no doors, no screens, no ability to shift or start. Two mechanisms drive it. First, the truck does not always fully power down when the driver walks away: owners report having to press the start/stop button on exit or the vehicle stays awake, and a key fob left near the truck repeatedly wakes it. Second, several body and propulsion modules shipped with calibrations that drew excessive current from the 12V system, and the vehicle only polls 12V state roughly once a day, so it does not catch the decline in time to top the battery up from the high-voltage pack. Owners have documented trucks going dead after sitting six days in a garage at 90% state of charge and unplugged. Secondary symptoms once voltage sags include a "conditions unable to shift" error and assorted software malfunctions that clear after a 12V jump.

On the 2022-2025 GMC Hummer EV, gM bulletin PIT6144G documents 2022-2025 GMC Hummer EV owners reporting that the air leveling suspension stops working, with a "Service Leveling System" message in the driver display and DTC C1197 SYM92 stored in the automatic level control module. On a truck that weighs over 9,000 pounds and relies on the air springs for both ride height selection (including Extract Mode and off-road heights) and automatic load leveling, a dead compressor leaves the vehicle stuck at a fixed height and unable to compensate for payload. GM identifies two causes: a plugged or pinched air inlet hose feeding the air suspension compressor assembly, and a software condition in the automatic level control module. Separately, owners have documented rear dampers losing fluid after moderate off-road use - one 2024 pickup took two months at the dealer to diagnose a right-rear damper leak, which was then covered under warranty. Fitting oversize (38-inch) tires has been reported to destabilize the system further and is not a supported configuration.

On the 2022-2025 GMC Hummer EV, hummer EV Pickup owners report that Super Cruise, a headline feature of the truck, works inconsistently - repeatedly refusing to engage on the same stretches of interstate and tollway where it worked before, and dropping out mid-drive. The dash messaging varies between "Super Cruise Not Available" and "No Road Information." Two distinct causes appear in owner reports and dealer diagnosis. The first is connectivity: the system depends on the OnStar/AT&T data connection to pull map and GPS correction data, and in weak-coverage areas it will not arm; owners describe being bounced between GM, OnStar and the dealer with each blaming the others, and some trucks needed the Super Cruise activation/subscription state fixed on the back end before the feature would work at all. The second is software or the module itself - dealers have applied GM's vehicle-wide Ultium software update (all modules) under bulletin 24-NA-143, and in some cases replaced the Super Cruise module outright and reflashed it to the newest patch, which resolved the dropouts.