2025 GMC ACADIA Service Brakes Problems

Brakes have failed now three separate times. The brake pedal becomes firm and the car will not stop or slow at all. I am pregnant and also had my toddler in the car with me. No warning symbols on the dash. Taken to dealership after several weeks of communication saying this was a safety issue and received a loaner vehicle. However, they have said if THEY cannot reproduce the issue, we will just get our car back. This is unacceptable. This is one of five issues we have already had with this vehicle.

While driving vehicle, multiple warning codes appeared including: service traction control, ABS, service brake system and others. More importantly, the power brakes failed and a code was thrown to press hard on brakes to stop vehicle.

I have the little feature that will brake for me if it thinks ima get in a wreck. However it’s glitchy!! I can be the only vehicle on road in BOTH directions, cruise set at 60 when out of nowhere the car slams on the breaks. We go down to like 52 then like nothing ever happened we are back to 60. This has happened several times. I have brought the car into my dealership tomorrow have the software updated and the camera recalibrated. Even after these steps were made this issue is still occurring. Happens about one to two times a week, so pretty often. My worries that I will be rear ended one day if this is not corrected.

We had complete brake system failure while driving the car on the highway. The brakes went all the way to the floor when applied and we came inches going into fast moving oncoming traffic before the vehicle stopped. I had to push the break with both feet with all the strength I had to get the brakes to respond at all. The brake assist failure warning light came on and another warning light came on that said SERVICE ESC. I have this on video. This was the first time the warning lights have ever come on. It’s a brand new 2025 car with only 800 miles on it. We were advised by the dealership who sold us the car to get OnStar to tow the vehicle to our local GMC dealership where we bought the car. When the car was hooked up to the diagnoses machine it said brake system failure. I have not received any invoices or paperwork to send you at this point. All I can upload is a video of the warning lights that were appearing on the dashboard after the incident.

While driving my 2025 GMC Acadia Denali on [XXX], from Omaha, NE, to Laurie, MO, I received a "Service Brake Assist" warning lamp as well as "Check Engine" and "ABS" warning lamps in St. Joseph, MO. At this point, my vehicle had 6,945 miles on it. We turned around and went back to Omaha. We dropped the car with Gregg Young Chevrolet at 7,095 miles. The dealership identified the issue as EBCM and master cylinder assembly failure. It replaced the EBCM and master cylinder assembly, test drove the car 7 miles and told me my Acadia was ready to go. I did not make it out of the dealership parking lot before the "Service Brake Assist" and "Check Engine" lights came on again. The dealership again identified master cylinder assembly failure, again replaced said assembly, test drove it 10 miles this time and told me my Acadia was ready to go. I got my Acadia and made it 1.1 miles before the "Service Brake Assist" light again came on. I promptly returned my Acadia to the dealership, where it sits today. At the date I am typing this (9/14/25), the dealership has had my Acadia since 8/22/25. The master cylinder has now failed 3 times at this point. First, after 6,945 miles, second after 7 miles, third after 11 miles. The safety of myself and my family was put at risk by the potential failure of my brake system. This should not happen on a brand new car with less than 7K miles and darn sure not 3 times in a row! Yes, the problem has been confirmed by the dealer 3 times. The dealership is now reaching out to GM to determine what to do. I don't have personal knowledge as far as inspection of the component by the manufacturer. It is my understanding from reading about the issue, that both GM and the NHTSA are well aware of this issue and are investigating. I am also aware of pending class-action lawsuits regarding the brake assembly failure. The first time I received the warning lights is when the system failed (or was starting to fail). INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 5

Bought new 2025 GMC Acadia in March of same year. At ~4500 miles I started getting Brake Assist, Forward Collision and Electronic Stability Control warning messages on dash. Upon researching, this is an increasingly common issue with this vehicle that can render the brakes unusable. I no longer feel safe in the vehicle and want it refunded. Car is now in the shop. Taken in on 9/11. Problem has been confirmed by dealer.

I purchased the car on [XXX]. Drove the car about 8000 miles and then all of a sudden the dash lights all lit up for the brakes, ABS, traction control. I pulled the car over and turned it off. When I restarted my car, the lights continued to stay on and it told me to service immediately. I called my dealer and they could not get me in within 2 weeks so I took it to another local GMC dealer who could get it in to look at it that week. I took it in on July 9th, and then received a called a couple days later telling me that it had a bad Brake control module that they needed to order. A week later was told the part was on backorder. Two weeks later was told the part came in but it was still missing the brake master cylinder and reservoir. At that time, I was told the ETA was unknown and I have been calling back every week. On August 23rd I filed a complaint with GMC and have struggled to get anywhere with them. They tell me the dealer has the parts and the dealer tells me that they do not. I still have no ETA and it has been officially 2 months without a car. I am told that it is not safe to drive. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Brake assist warning message and BRAKE light appeared a couple of weeks ago, along with others. Brought the car into the dealer, who initially thought they cleared the errors and reported no additional issues when they ran the diagnostics. Nothing was cleared. Vehicle application and monitor also does not show an issue, even though the warning appears at each start up and none of the related safety systems work (ABS, ESC, AEB, etc.) that rely on the brake pump. Information from the dealer and owners manual are in conflict, with the dealer allowing me to drive while the owner's manual indicates it should not be driven with the BRAKE light lit. They have now "diagnosed" a "failed" master cylinder unit that includes electronics and the pump. The car had about 4500 miles on it when the issue occurred. I am at a loss for if it should be driven and trusted or not.

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

dash lit up with ABS, traction control, and ESC warnings. Technician stated the entire brake system needed to be rebuilt. There is currently no ETA on when the parts to be able to accomplish this will be available.

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.

Vehicle had a "service ESC" and "service brake assist". Dealership said the master cylinder is bad and it is not safe to drive. Now its sitting at the dealership with NO eta on parts and no loaner cars.

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.

At approximately 4900 miles, the brake master cylinder failed on my vehicle. It has been at the dealership for over a month awaiting parts for repair.

Multiple brake warning lights came on while driving vehicle

Car driven off the lot 06/14/2025 On Sunday 07/06/25 (21 days from purchase) while driving home from a 30 minutes away from home trip with 3 young children with me, the car gave multiple alerts and service warnings. "Service Brake Assist" and "Service ECS" Lights / Symbols related to the following were also displayed: Traction Control System (TCS)/ Electronic Control Stability Light, Anti-lock Brakey System (ABS); Brake System Warning Light, Forward Collision Alert and BREAK light I stopped the car immediately and pulled to the side of the road. After restarting vehicle, lights were still displayed and service alerts still on. Power steering was very diminished and the breaks were struggle to break. Acceleration was also impacted and every time I breaked it appeared as though the car was trying to accelerate. I was able to drive the car home slowly following back roads. On Monday 07/07/25 I called the dealership and arranged a tow to their facility. On Tuesday 07/08/25 after multiple "unavailable to take your calls" I was finally able to connect with a service technician who indicated the break master cylinder needed to be replaced. I was not given an ETA on the completion of this repair. I have owned the car for 21 days. It has 1073 miles on it!!! I have 3 young children! The original route home was via a very heavy interstate! What if the brakes failed me while driving an interstate! I praise God I was able to get home safely with my children

ABS, EBCM, Traction Control and brake lights on.

After having vehicle for one month, a "service brake assist" message was displayed on instrument cluster. Vehicle was taken to dealership for service and was told the master brake cylinder needed to be replaced and will take a while due to a nationwide shortage on the part.

After having my 2025 GMC Acadia Elevation for 2 weeks, I turned it on and six lights on the dash lit up. ESC, ABS, Tractions Control and more. I was leaving a store at the time this happened and drove home. Also, my cruise control would no longer work. Took my Acadia to the dealership the following business day to be serviced, only to be told a week later that the master brake cylinder needed replaced. This part of course was on back order. My new part arrived two weeks later, only to discover that two additional one-time parts (seal and reservoir) are now needed. These parts are also on back order with an estimated ship date of mid to late July.

The ESC, ABS, and Traction Control, Yellow warning lights, BRAKE, Red Warning light. Diagnosis is ABS, module, and master brake cylinder bad 2025 GMC Acadia Denali, 1150 miles. No parts available because these are all needing work! People are having near misses and collisions due to this problem! Put a stop production order until these are fixed!

I have had my 2025 GMC Acadia Denali for 1 week with 336 miles on it. When I went to start it on the evening of [XXX], I felt the brake pulse. Then the dash lite up with message to Service ESC. The brake icon was lite up red and ABS was lite up yellow color. I took my vehicle to our local Jeff Fender GMC dealership the next morning. The service tech did a brake pressure test which passed. He cleared the codes. When I went out to leave the dealership, the codes came back on. The service tech said it is NOT safe to drive because my brakes can fail at anytime. Service said they need to replace the master cylinder. With this issue, my brakes could fail & a horrible crash could occur causing injuries and/or death. Service rep told me this has happened to a new Yukon too. My husband called the dealership in Lake City, FL, where we purchased the Acadia from & spoke to a service rep. He told my husband he has seen this in Yukons, Terrains & Sierra pick up trucks. This brake issue with the master cylinder should be a recall due to the potential dangers of a horrible accident that can occur if the brakes fail. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)