Which parts fail
Components named in complaints (battery, alternator, wiring, ignition, instrument cluster, infotainment).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 2018 GMC Terrain owners, lightly cleaned up (personal details are redacted by NHTSA).
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.
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.
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. …
1. 2018 Terrain would not start in a parking lot. Remote was used after several attempts to start with push button failed, and after a slight hesitation , engine started. Vehicle was driven about 6 miles without incident. 2. Vehicle was driven about 10 miles the next day and start/stop engaged at a stop light but would not restart. After about 3 minutes of cycling throught the starting procedure, the vehicle started. Drove another 8 miles without incident. 3. Next morning, drove about 3 miles to intersection where start/stop engaged but would not restart. After about 30 minutes of cycling through starting procedure and an attempt to jump start was made the vehicle restarted. At this point, the vehicle was taken to Romain GMC for service. A new battery was installed and other related operations.After about 10-15 miles, the vehicle would not start. …
The "Service Brake Assist" issue in other 2018 GMC SUVs is happening in the 2018 GMC Terrain, but it is not part of the recall. Our brakes became EXTREMELY difficult to press right as we were turning onto the on ramp of an expressway. Thankfully we were smart enough to pull over and not get on the highway. Had we done so, I may not have been here to type this complaint. The brakes be come extremely difficult to press and that message shows. Dealership is going to charge me $400 to replace a vacuum pump - they were not interested in the information I have around this issue in other GMC SUVs since it isn't a formal recall on the Terrain. I could have died yesterday due to this braking issue. I've owned this car for 3 months.
Multiple warning lights are appearing at once (Automatic brake assist, forward collision assist, parking brake released) When the car is put in reverse, the radio turns off for a brief moment and the steering assist warning shows on the dash. The steering wheel snatches back in the opposite direction causing a safety concern. The car also completely cuts off after the auto-stop takes effect at red lights causing me to have to pump the brakes at least twice to re-ignite and be able to accelerate.
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.
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.
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
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 [redacted] 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. [redacted]. …
Electrical complaints in other Terrain years
Frequently asked questions
How common are electrical problems on the 2018 GMC Terrain?
NHTSA has 35 complaints about the electrical system of the 2018 GMC Terrain, 16% of the model year's 225 complaints. The component named most often is adas › blindspot › sensors (1 mentions).
Is there a recall for 2018 GMC Terrain electrical problems?
No. NHTSA lists no electrical system recall for the 2018 GMC Terrain, though it has 5 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 2018 GMC Terrain electrical problems start?
Half of the complaints with a recorded mileage happened before about 22,000 miles, and 53% before 25,000 miles.
Is it dangerous?
Owners linked 1 crash, 1 fire and 0 injuries to electrical system problems on this model year. If you notice symptoms, have the car checked before driving further.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.