2025 GMC Acadia

Purchase vehicle on August 13, 2025 with 27 miles on it. Drove home from dealership. Started the car on Friday morning and all of these warning lights appeared - Electronic Stability Control, Brake Assist Service, Brake light indicator, ABS indicator, traction control indicator, collision warning indicator. Car only had 69 miles at the time. Took vehicle to dealership on August 18, 2025. After diagnostics were performed, it was determined that the Master Brake Cylinder is the issue. The part is on back order and there is no estimated time of when the part will be received and installed. Dealership Rep told me that it was safe to drive the vehicle to the dealership. Service Technician then explained to me that I should not be driving the vehicle.

I purchased the vehicle, and twelve days later while operating the vehicle I experienced full braking power failure. My foot was to the floor board while trying to get the car to slow down. Up until the point of brake failure, there were no warning lights or "symptoms" that would alert me as to an impending problem. My young child was also in the car so that was extremely scary also. During this time, the "service brake assist" light and ABS light came on. I was able to slow the car down enough, restart the car, and the brakes seemed to work, however all of the related braking lights were on my dash. It was brought to the dealer the next day. The dealer has noted that its the master cylinder that needs to be replaced. However, they replaced it, and the new master cylinder has also failed, so they'll need to try and replace it again. I'm concerned this issue could cause severe accidents in the future if it continues to not be addressed.

Upon starting the vehicle the vehicle immediately starting moving while foot on brake and moved from park to reverse or drive. Unable to stop the vehicle in idle gear and no gas pedal applied. Power steering warning and no brake assist warning on the dash. Unable to stop vehicle within 20ft while traveling at idle speed. Vehicle lights and warnings have been reproduced and is currently at a dealership awaiting further inspection. Vehicle is available for third party inspection if needed. Vehicle at Barker Buick GMC, 6444 W Main St, Houma, LA 70360 on 8/4/25

Approximately July 12 2025 while driving to dinner two warnings showed on the Driver Information Cluster (1) Check Brake Assist (2) Check ESC. Took vehicle to dealer the next business day for diagnosis. Service department stated the problem was the EBCM or Electronic Brake Control Module and the parts are on a Nationwide backorder. Since the part failure all brake system associated lights on the gauge cluster are illuminated and non of the associated safety systems are functional including but not limited to ABS, Stabilitrak, Lane Keep Assist, Adaptive Cruise, Crash Avoidance or standard cruise control.

At startup today vehicle displayed “Brake Assist Failure. Press Hard to brake. Speed limited.” It also displayed “service.” It also displayed “ESC,” and the word “service. An internet search indicated this may be a common problem of this vehicle, caused either by a software error in the Electronic Brake Control Module, or due to a defective brake master cylinder. There is a GM service notice for these defects, N242471431. Regardless of the cause, the brake is extremely mushy, and requires a high degree of force to stop the vehicle. GM says there is no recall due to this defect. This is a brand new vehicle and therefore it must be a defect in the vehicle. Given that braking is a fundamental safety issue, it’s hard to believe there is no recall already issued.

New 2025 GMC Acadia Denali vehicle with only 5,600 miles driven. When starting SUV I pressed start button and brake pedal. I felt the brake pedal pulse down. Once started, the dashboard lit up with warnings of Service ESC and Service Brake Assist. Quickly took to dealer, they ran diagnostic tests and revealed the Master Brake Cylinder is out. Dealer said I should Not drive it due to danger of brakes completely failing! Dealer has other 2025 Acadia's come in with no brakes at all due to same issue and they are still there waiting on same part. Dealer and GM have NO estimate of when they will have a new Master Brake Cylinder as this part is on back order. A case has been created with GM regarding part availability delay. My research has revealed numerous owners of 2025 Acadia, Traverse and Enclave with this same Master Brake Cylinder failure and no parts available waiting months. Brake failure is a MAJOR SAFETY hazard! GM has stopped selling the 2026 Acadia, Traverse and Enclave. They should recall all 2025 Acadia, Traverse and Enclave!

My car has less than 8,000 miles currently. On June 5, I started my car and lights were on saying I needed service and maintenance. I believe it was around 4500 miles at the time. I took it in once, where I bought my car, they said it just needed an update. The next day, all of the same lights were on. Turns out, I need a new brake master cylinder. It’s on back order. I bought this car in April. It’s been in the shop for a month. This is ridiculous. - the notifications said I needed electronic stability control and service brake assist maintenance.

Brake Master Cylinder failure. Received warning lights on the dash and took to the GMC dealer for the diagnosis. Dealer stated the car is not drivable because the brakes could fail. The head mechanic at the dealership confirmed that the cylinder is the problem. They had no idea as to how long it would take to find a replacement cylinder.