2018 GMC Terrain electrical problems

Filed Dec 11, 2025 · Electrical · CT

The infotainment system will just randomly start going haywire and when it happens, you cannot use the touchscreen. It will try to randomly delete app icons such as the camera, it will try to delete connected phones, it will try to delete radio favorites and it will move app icons all around. These are just a few examples of things that happen.

Filed Nov 7, 2025 · Electrical, Locks · 130,000 miles · DE

The contact owns a 2018 GMC Terrain. The contact stated that the transmission was shifting gear erratically. The contact stated that the doors were locking and unlocking independently, and the instrument cluster was blank. There was an abnormal beeping sound coming from the vehicle. Additionally, the contact stated that while at a traffic light, the Auto START/STOP feature delayed to respond. OnStar was alerted, but the contact declined to perform the service. The contact was in contact with the independent mechanic who sold the vehicle, but no assistance was provided. The local dealer was contacted. The vehicle was not diagnosed or repaired. The manufacturer was contacted, but no assistance was provided. The failure mileage was approximately 130,000. The VIN was not available.

Filed Aug 28, 2025 · Electrical · 77,000 miles · OH

The contact owns a 2018 GMC Terrain. The contact stated that on several occasions while driving at various speeds, the infotainment system screen and radio inadvertently switched stations from AM to FM. On other occasions, while driving and using the GPS system, the screen went blank. The contact stated that on several occasions the screen was turned off, and on other occasions, the screen was turned off and on however, the failure was temporally fixed. The vehicle was not diagnosed of repaired. The manufacturer was not notified of the failure. The failure mileage was approximately 77,000.

Filed Jul 14, 2025 · Brakes, Electrical · WV

Component Affected: Service Brakes, Hydraulic – Brake Vacuum Pump Summary of the Problem: I am reporting a serious safety issue involving the brake vacuum pump on my 2018 GMC Terrain. The brake pump failed catastrophically ("blew up"), resulting in a sudden loss of braking power. This occurred without warning and posed a significant risk to my safety and others on the road. We were traveling to vacation in Florida and thankfully had just gotten off the interstate. Details: The failure caused the brake pedal to become extremely hard to press, and the vehicle required a much longer distance to stop. We experienced no brake at the brake booster and a blown vacuum pump is due to a faulty vacuum pump which is a known issue for this model. Fortunately, no accident occurred, but the situation could have easily led to a collision. A certified mechanic confirmed that the brake vacuum pump exploded and needs to be replaced. I have incurred significant out-of-pocket repair costs due to this issue. We had to uber to our vacation room, get Walmart Plus to have groceries delivered to our room. We had to have Uber Eats deliver other supplies. We have had to walk to various places for dinner and entertainment because Avis and Budget had no vehicles available to rent and Enterprise was closed as we arrived on Saturday afternoon. I have checked for recalls and service bulletins using my VIN, but none are currently listed for this specific issue, despite similar problems being reported in other GM vehicles. Request: I urge the federal safety agency to investigate this issue further. The failure of a critical braking component without warning is a serious safety concern. I believe this may be part of a broader pattern of brake system failures in GM vehicles and should be addressed through a recall or safety campaign. Also, the estimate for the repair is $2,500 so any reimbursement would be greatly appreciated. We just received this estimate but I can provide it at a later date.

Filed Aug 27, 2024 · Electrical · SC

The contact owns a 2018 GMC Terrain. The contact stated while driving at an undisclosed speed, the contact became aware that the horn was inoperable. There was no warning light illuminated. The vehicle was taken to the dealer. The vehicle was not diagnosed or repaired. The manufacturer was made aware of the failure. The failure mileage was not available.

Filed May 13, 2024 · Brakes, Electrical · KS

Safety was put at risk when brakes went out without warning, and unable to use emergency brake at that time. Car was serviced for over $1700, with the mechanics stating that the piece “blew up.”

Filed Feb 25, 2024 · Body, Electrical · CA

Rear side windows in hatch area leaked filled up spare tire compartment with about 3-4 gallons of water. Now navigation doesn't want to work, sunroof not working, electric systems are not working right

Filed Jan 7, 2024 · Electrical · OH

The door locks began to have issues; the locks started to work only occassionally for no apparent reason. I've been locked out of the car several times and had to use the auxiliary key. Plus I couldn't lock the car while I was inside as the interior door lock button wouldn't lock or unlock the doors either. It's not a kefob or battery issue and no lights on the dashboard. The dealer reports that they couldn't reproduce the issue. However they found corrision on the electrical harness inside the passenger front door. I replaced an electrical harness in the rear bumper 18 months prior for corrision found. The dealer says they received a service bulletin on the "electrical harness" issue however the dealer won't cover the cost of $500 to replace the harness. As this deals with the electrical system, my concern is that it may effect the operation of other components of the car while it's running. Safety and security is of the utmost importance whether at home or away as it regards to being able to lock or unlock the doors.

Filed Dec 12, 2023 · Electrical · AZ

On Wed., Dec. 6 around 3:15 pm during heavy traffic on FWY [XXX], cars slowed down to a brief complete stop. When I went to start slowly as traffic began to move, engine completely shut down. I could not open windows or my door to get out of vehicle. Immediately called 911 and was transferred to DPS. It took approximately 65 minutes before I had help and was finally towed from the dangerous freeway lane where I was stuck and with vehicle completely stalled and locked down, I couldn't even get car in N to be able to have help moving to a non dangerous place outside of the FWY lanes. This is the fifth time this car locks down. I've learned to open a panel by the foot brake area, pull a lever in that area and be able to move the car to a safe location until I got towed into the dealer. It is the second time that this has happened in a potentially dangerous street and now Freeway. Danger to myself and many others that had to maneuver around me. The first time (around 2020) the car totally shut down, it was reported that a computer harness had to be replaced. This last time I was faced with such a dangerous situation on a FWY it was determined that the ECM (Engine Control Module) had caused the shutdown and locked the vehicle to where I could not even get out for close to an hour. The ECM was replaced by GM and the car is running again, but my shock and trauma still haunt me as to the self and others danger that was present. . GMC Dealer finally determined after several attempts that ECM was the problem. Unsure if available to inspect it. Delivered car back 12/8. . Heavy freeway traffic at peak hour put me and many others in serious danger. . My dealer report reads it was difficult to diagnose and finally find ECM was the problem. .Vehicle has not been inspected by Manufacturer, police, or insurance. .A few minutes before this lock-down an engine icon appeared while on the FWY. Previous shutdown incidents had no warnings or messages before locking up. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFO

Filed Dec 4, 2023 · Electrical, Engine · IL

There is an has been an issue with my electrical system says I purchased this car in 2017. Myself believe that the issues have not been documented until 2020. When my racy begins to run out, my engine light has been coming on and I’ve been getting the same code P1101 I took my vehicle to GMC and they told me that the engine light came on because the tape came loose. I brought this vehicle and there’s no way there should be no tape on it. The service tech also told me that if the problem continue to bring it back and I will have to pay $120 or whatever the label rate was for them to research I contacted GMC to file a complaint and I received the whole bunch of calls from a guy named Kevin. I believe he told me that he had been contacting [XXX] and no one returned his call and that he was sorry he couldn’t help me. This is my report number one of them from GMC. [XXX]. Everywhere I take my car they tell me that they have a lot of customers with the same issue and they tried to replace what the code is matching which is the mass airflow sensor but that does not help there is some type of problem with the engine or the electrical system with this vehicle. I am not the only consumer that has had this problem. I don’t know what to do. I have two kids I cannot afford to keep pay and label rate for them not to find the problem. I am also attaching the typical email that GMC sent out when they are working with the dealerships because I have been in contact with them and the person that was calling and then they sent me this email. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)