GMC Complaints

My HMI was "bricked" when onstar pushed an incompatible update when I changed the service plan. While driving the screen has intermittently turned off and on causing temporary unexpected loss of navigation functions, Bluetooth connectivity, and use of the back up camera. This causes a safety issue as the unexpected loss of display and connectivity has caused me to be unable to continue using hands free features during operation, and to no longer view behind the vehicle during entirety of backing. When I contacted OnStar support I was instructed to perform some troubleshooting and was then referred to the Connection Center Team. The CCT representative told me that my hardware was outdated and could not support the update. If a representative can confirm the problem retrospectivly, I think the representatives making changes to the service plan should also be able to proactively confirm incompatibility before causing the issue. There were no warnings. The issues first occured while I was driving on the day (6/25/26) my new plan began and the update was sent. I can make the HMI available for inspection upon request. I don't believe there is any actual issue with the hardware, just a negligent and incompatible software update.

Truck shut off and would not turn back on. Negative battery cable so hot it burned skin off. Would not start, tried to start clicking sound, radio blipped for a moment.

The contact owns a 2008 GMC Envoy. The contact stated that while the vehicle was parked on several occasions with the driver's side seat belt latched, while attempting to release the seat belt, the seat belt remained locked in the buckle. The contact depressed the release button and wiggled the seat belt several times before the seat belt released. On one occasion while the passenger’s seat was occupied, the seat belt failed to release while depressing the seat belt release button. The contact exited the driver's seat and attempted to assist the passenger to release the seat belt; however, the seat belt tightened around the abdomen. The contact stated that a bystander attempted to assist, but the seat belt failed to release and became tighter around passenger’s abdomen. The contact used a pair of scissors to cut the seat belt webbing to release the passenger. The contact was unable to remove the seat belt even after cutting the webbing. The passenger was not injured and did not receive medical attention. The vehicle was taken to the residence where the contact's spouse inspected the vehicle and attempted to release the seat belt. The vehicle was not repaired or diagnosed. The manufacturer was notified of the failure. The failure mileage was approximately 138,735.

Trailer brakes continuously fault due to known problem GM technical bulletin 23-NA-149 This should be a recall. Nothing but the runaround getting it fixed by GM.

Issue Description: The vehicle experienced a failure of the Dynamic Fuel Management (DFM) system, resulting in a collapsed lifter. This caused a cylinder misfire and a sudden loss of engine power while driving at highway speeds. Safety Concern: While traveling at highway speeds, the sudden misfire and loss of power created a dangerous condition. The vehicle could not maintain speed or accelerate properly with surrounding traffic, significantly increasing the risk of a collision. Failure Details: The issue was diagnosed as a collapsed lifter related to the DFM system. This caused persistent misfiring, rough engine operation, and severe drivability issues. Repair Outcome: Due to the extent of internal engine damage caused by the lifter failure, the vehicle required complete engine replacement.

Failure to release parking brake. Lining material improperly bonding to steel shoe from Manufacturer. Service Parking Brake warning Indicator “on”

This vehicle became subject to a manufacturer safety recall requiring complete engine replacement. The engine failure has been confirmed by an authorized GMC dealer, and the vehicle has remained out of service for more than one month while awaiting the recall remedy. The dealer has advised that the repair has been escalated through GM's SPAC (Service Parts Assistance Center) process because a replacement engine is not available. General Motors has also confirmed there is currently no estimated delivery date or estimated completion date for the repair. As a result, the recall remedy is effectively unavailable, and the vehicle remains unusable for an indefinite period. Although a temporary loaner vehicle has been provided, it is not functionally comparable to the recalled vehicle and does not provide the towing capability and utility required for its intended use. The vehicle was inspected by an authorized GMC dealer, who confirmed that engine replacement under the recall is required. The vehicle remains available for inspection. My concern is not only the original safety defect but also the inability to obtain the recall remedy within a reasonable timeframe. There has been no estimate of when replacement engines will become available, leaving the vehicle out of service indefinitely. I am submitting this complaint to document the delay in completing the safety recall and to request that NHTSA review whether the recall remedy is being provided in a timely and effective manner.

The front grille/hood trim flew off driving down the highway. No, it is not available the cheap plastic shattered. My safety was put at risk b/c parts are flying off the truck that should never. More importantly other people's safety is put at risk b/c a long SHARP plastic piece is flying off a large truck driving down the highway!! Yes, Glenn Polk has seen the damage and can confirm. No, no one else has inspected it yet but you gladly can, it doesn't take a genius to see that the cheap POS plastic was terrible engineering by GM. There were no warnings or indications that the piece was even loose.

I was pushing the accelerator, and the transmission hesitated at about 45 mph. For about 2-3 seconds, the vehicle would not upshift. The RPMs revved, and finally the vehicle slam-shifted into gear. The vehicle drove normally for the rest of the drive cycle.

Formal Safety Complaint – 2021 GMC Terrain Brake Failure Vehicle: 2021 GMC Terrain Incident Location: Garden State Parkway (NJ) Speed: Approximately 65 mph Incident Description While driving northbound at highway speed, I attempted to change lanes and apply my brakes. When I pressed the brake pedal, it became completely rigid (rock hard) and failed to function. I had no ability to slow the vehicle using normal braking. At that moment, I was forced to: Navigate multiple emergency lane changes to avoid striking other vehicles Prepare for potential collision due to lack of braking control Apply extreme force with both feet on the brake pedal in an attempt to generate any slowing Eventually, I was able to steer the vehicle to the shoulder while exerting maximum pressure on the brake pedal. During the incident, a “Driving Assist Brake” message appeared on the dashboard, and the braking system has remained in this same compromised condition since. Safety Concerns The brake pedal became non-functional without warning The failure occurred at highway speed, creating an immediate life-threatening situation This was not a gradual degradation—this was a sudden, complete loss of braking capability The issue persisted after the vehicle was stopped Broader Concern I have since found multiple reports and videos of other GMC Terrain owners experiencing the exact same failure, suggesting a potential systemic or design-related issue. Given: The severity of braking system failure The apparent repeat nature of this issue The lack of an active recall addressing it I believe this represents a significant safety risk to GMC Terrain drivers and the public. Impact This incident caused: Immediate danger to my life and other drivers Extreme emotional distress Loss of confidence in the safety of the vehicle Requested Action I am requesting: A formal investigation into this braking failure Immediate inspection and repair of my vehicle at no cost Clarification from GMC regarding know