2020 GMC Terrain Problems and Top Complaints – Is Your Car A Lemon?

Vehicle speed control, electrical system and powertrain issues among the top complaints received by the NHTSA from vehicle owners

The 2020 GMC Terrain is a luxury-minded SUV that is designed to elevate the experience for customers. In fact, the GMC motto is “Like a pro,” but in this case, owners feel that the automaker missed the mark. For the time being, the Terrain seems to have a malfunctioning powertrain, vehicle speed control and electrical system.

Click on other model year to view more problems: 2018      2019

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Problems with the Transmission

The powertrain is supposed to be designed with a robust transmission that supplies energy to the wheels. However, this Terrain SUV is struggling to perform.

One Edmunds user puts it simply by saying, “Trans whines between 20-28 MPH.”

But, the issues go deeper than just the transmission making noises. Service Bulletin #PIP5720A also talks about one of the many major issues with the powertrain. It states that there could be a transmission fluid leak noticed, which looks like residual fluid from assembly. To determine if it is still leaking, a complete cleaning is required. New vehicles should not have any type of transmission fluid, whether it is currently leaking or was previously an issue. This doesn’t convince anyone that GMC knows how to do things “like a pro.”

Problems with the Electrical System

A vehicle’s electrical system has a big job. It must start the engine, run all of the accessories and supply up-to-date technology to picky users. When this system begins to fail, no one is happy.

Here is a complaint worth reading, left on the NHTSA website. “Every week it’s something different. In motion…no cruise control. No audio. Don’t drive over 50 mph brake problem. Parking brake engages randomly and without user engagement. No AWD. No Stability Traction. This happens so frequently the dash indicators have been reduced to Idiot Lights. At what point do I become concerned? Things appear to resolve when the engine is turned off and back on, sometimes…I compare it to other glitchy technology. However, I potentially could be at an 80 mph cruising speed when I decide to ignore the idiot lights…what happens when a real problem presents and I ignore the dash indicators due to frequent glitches? I’m so disappointed. My 2 previous Terrains were 10 times the vehicle the 2020 model year.”

It turns out that there are so many electrical system problems that GMC can’t keep up. One of the communications, Service Bulletin #PIT5745, talks about how the memory seat module can wake up the Lan BUS, leading to a parasitic battery draw. There’s nothing worse than running out to the SUV in the morning only to find out that the battery is dead and getting to work on time becomes impossible. This is a real problem, especially if the owner wants to make the money to pay the higher Terrain payments.

Problems with the Vehicle Speed Control

The vehicle speed control is designed to help cars move at a specified rate, without much operator input. When this system fails, a lot of people are put at risk, as is seen with the Terrain.

Another NHTSA complaint states, “When cruise control is engaged at 71 mph, holding +Res Button to increase speed and releasing it at 77 mph sets cruise speed too high. Car continues to accelerate. Cruise gets set at 100 mph and accelerates more than desired.”

When it comes to this defect, GMC doesn’t want to talk about any problems. Instead, the automaker has allowed customers to drive blindly down the road, not knowing that it could accelerate on its own. Apparently, the Terrain is so focused on being a “Pro” that it also wants to move every other vehicle out of its way on the road.

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About the Author:

Brian Jones spent more than 20 years working as an ASE Certified Master Tech and Parts Specialist at multiple dealerships. Brian has become an authority in the industry, traveling across the country to consult for car dealerships and contributing his expertise as a writer for several major automotive publications. In his spare time, Brian enjoys working on pickup trucks, muscle cars, Jeeps and anything related to motorsports.

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  • Pam D

    I own a 2020 Terrain and love it. 5,800 miles so far and it’s only been taken back to dealer for scheduled maintenance. I sure hope it stays this way. I am always concerned about the engine constantly cutting off and on again. Now I don’t even notice it. There are lemons, I know, years ago I bought a new Jeep Grand Cherokee and had to return under the Texas Lemon Law. I sure hope the best for the GMC Terrains and their owners.

  • Dennis A

    Lights and turn signals fail regularly, Repeated trips to dealer for repairs, problems are intermittent and they day bring it in while is happening. Of course, when the car is switched off and bac on there appears to be no problem. Power train is sometimes jerkey at 55 to 60 mph. It usualy, takes me some time to hate a car,but not this thing,3 weeks in I hated it.

  • Michon H

    We purchased our 2020 denali Terain a year ago and have had it into the dealership 4 times now due to check engine light coming on. The first time they said it was a sensor, but of course it went off the day we took it into the dealership and told that if it comes on again bring it back in. The second time the check engine light came on I took it and they “supposedly” replaced it. Then it came on a 3rd time, this time I was told that the “motherboard was bad” supposedly they replaced the entire system. Just last week the check engine light came on again. Just took it into the dealership again to find out what it is this time.

  • Reem I

    My problem in terrain 2020 is that car’s smoke enter my car cabinet when ac/heater is turned on even during internal circulation mode.
    I bought it brand new from gmc agent in jordan and they told me that problem can not be solve

  • Casey H

    I purchased a new 2020 Terrain with 32 miles from a local GMC dealer. At 350 miles the power steering failed, nearly causing me to crash. The entire steering column was replaced by GM at mile 1,140. Now at mile 3,900 there was a loud pop under the hood, while driving with the cruise control set at 60mph, and the vehicle is in limp mode with the check engine light on. The engine stalls at low rpms and it looks like I’ll miss work to take it back to the dealer tomorrow. I’m ready to be rid of this thing!

  • Dave M

    Every manufacturer and vehicle model has lemons no doubt. Your comments here make it sound as though all GMC Terrains have terrible problems. Being in IT, I know you can look on forums for software/hardware problems and you will find them to the point you will wonder how the product even works! I own a 2020 GMC Terrain Denali for over a year now and have experienced none of these issues — I hope I don’t — and expect the vast majority of owners will not.

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