2020 GMC TERRAIN Electrical System Problems

Towards the tail end of a nearly 2.5 hour drive, the Automatic Theft Deterrent System was activated on the interstate. I lost every display on the dash panel including my speedometer, battery, coolant, gas, turn signals, and windshield wipers. I went into the nearest parking lot and was unable to restart the vehicle. It was towed to the dealership closest to our home and was repaired for $2200. The technicians at the dealership were not sure of what caused it and had never seen an issue like this so it was “elevated” to the GM engineers at their headquarters. They replaced the electrical control module and both key FOBs. We have not experienced any similar issues.

My a/c went out within 2 years of having the car in 22’. In 2025 i have had nothing but problems, the radio will go out when im driving for about 2 hours and it resets, the screen goes black, music stops, navigation stops and then it turns on like nothing happened. It happens everytime I drive 2+ hours. Back in September of 2025, I was on my way to work when I was stopped at a red light, it turned green and then my brakes locked up and I couldn’t drive my car had shut off, and wouldn’t come back on. I was stuck in the middle of the road not knowing what happened as the car had driven fine up until i stopped at the red light. Then tonight November 21,2025 around 0315 I was leaving work, I started my car, my car threw up a message that said “Low fuel, 0 miles” I had half a tank of gas when I got to work. I turned my car off then back again and it did the same thing. I let my car sit for a second and then my Gas gauge started to slowly increase to the correct amount of gas. Then when I got home (3 mile drive from work) I turned my car off and then back on and this time when I turned the car on my brakes were locked and I couldn’t start my car. All of the Engine lights were on so I turned the car off and then let it sit for a minute before trying to start it. When I tried to start it this time, I couldn’t. It’s like the car had died and was getting no power. I couldn’t lock my car, no lights were working, I couldn’t turn it on or start it. Some time went by and my interior lights were on so then I started the car and it’s almost like my car reset. I can’t see my tires PSI, the clock went to midnight (it was about 0330) it was all just very weird!!

Break assist light comes on and brakes stiffen suddenly with no warning. Happened 6 times now in a 3 year span. Gotten it "fixed" each time but it keeps happening

Backup camera not working and has a blue screen. The camera was replaced. The fuses & wires were inspected and the screen remains blue.

Sunroof/moonroof/sunshade and frame leaking for 2nd time.

[XXX] once again while diving down the road 45mph Terrain once again goes in to park ,I was lucky the lady behind me wasn't to close .Also I contacted onstar when I was able to get vehicle moving at the store ..I told her what happen she ran diagnostics while parked at store said there was no codes I let onstar know this has happened several times..I had no warning, no indication, no lights came on.And I also let her know that this same vehicle was still stalling I was at intersection and the auto/stop is always on it will not let you bypass or default took it to dealership who I bought CPO back when it first would not let me turn it off cause its stalls at stop signs ,red lights etc crazy thing is if you turn the ac on it cranks up , if you hit the door unlock it starts... Thats not normal GMC knows that the dealership whom sold me CPO that wasn't the misleading is beyond crazy..GSM cussed me out It comes with life time warranty but when I had it towed right after I bought it 2 months ..I was talking about what the mechanics had said that this vehicle was in prior flood and accident GMC onstar has a different Vin then the one that on the vehicle..The doors are not original I can see the inside of steering wheel and on dash where they said air bags were deployed and they did a [XXX] job hiding it ... I paid over 32k for this 2020 Terrain that was advertised as CPO with 1 owner in Florida they showed me a fraudulent carfax, I pulled up my own and it came from New York ..This vehicle is not safe to drive but I dont have any other options..I have made complaint with both GMC and my finance company whom also wrote complaint on dealership and the told me I could rewind the loan but when I told dealership I knew that they sold me a vehicle that was not CPO and what I learned He came at me at dealership infront of workers and customers .. The vehicle just going to end up getting myself killed or someone else.. Semi had to run off road to avoid hitting me INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT

5.25.2025 - Car shut down while at a busy intersection. Called Amherst Police due to location and how dangerous the intersection was. Family member needed to jump start the vehicle. Vehicle started before police arrived. Drove home. Called police to let them know we were no longer at the busy intersection. 5.26.2025 Took out battery to check charge at Auto store - tested Good - 82%. Re-installed battery went to get gas thinking that may be the issue, low on gas, not the case the car wouldn't start at the gas station. Family member needed to jump start the vehicle again. Drove home, called dealer, taking to dealer next week 6.4.2025 due to availability of service. There were no warning lights prior to stalling out both times. This is very dangerous. We are afraid to drive this GMC 2020 Terrain.

Vehicle has not recently been inspected, backup camera has recently gone out leaving only a blue screen with "service rear vision system" to my knowledge nothing has happened to the unit that would cause this. Regular day to day driving, there was nothing that would have given me any notice that this would be happening.

My Terrain has a light that has been coming on for a couple months. Service Brake Assist. I took it to the dealer after my brakes locked up and about $800 after getting it fixed the light continues to come on. The forward collision light comes on every time I start the car. More the check engine light came on and says engine electrical system. What the heck is going on? I love this car and take very good care of it but I feel like the $800 that I just spent was a waste. I fear that I will get in a wreck like when the brakes totally locked up and I couldn't press on them.

The vehicle is a 2020 and should not already be having electrical issues. The vehicle repair is over 5k for needing a starter motor, water pump and drive belt. A starter should last up to 100k miles and water pump should last 10 years not 4. This vehicle is a lemon and should not have so many issues.

Purchased Vehicle brand new- Beck & Masten Buick GM - Houston, TX [XXX] Performed rout maint regularly. Last oil change 1-5-2024 before catastrophic failure and complete engine seizure. Towed to Wiesner GMC [XXX] 1-12-2024: Mileage on car roughly 99K- had no issues no check engine light, no mechanical failure or indication that anything was running other than normal. No Start on [XXX] PM after work, tried to return next day with battery , changed out battery, engine still would not start, after new battery installed and we attempted to start, that is when engine started making loud shaking motion while attempting to start, windshield wipers came on randomly. First initial diagnostic: Found all oils & fluids in check, could not identify cause of failure, would have to break down and take apart. Had to authorize the tear down at a 1800.00 cost, 2/2/2024: Broke down engine, found that the crankshaft would move one way , but not other, removed the engine from transmission and now crankshaft moves freely. Now the AC comp is locked up (excessive play on magnet & clutch) , tech still unable to identify what caused the failure, they advised that they found traces of metal in oil pan, scored cylinder walls, starter shorted as well. They still could not indicate where these metal pieces came from, how or that it was due to owner negligence or manuf defects. Again this is a vehicle with 99K Miles and now we were looking at a 15K price tag for a new engine, turbo, AC, starter on a car that is worth 12K. This is absolutely insane. We reached out for Goodwill Discounts for some assistance since the dealership could not solidify a cause of failure, but GM decided to not warranty and stand behind their product. We were left with a rebuild option for 7500.00. which we had to do in order to get the car back. I am completely disappointed in GM as a company. This engine should have never failed at 99K. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Driving down the road at 40mph when the car shifts to park, the brake and steering wheel lock up and the car won’t accelerate. I had to pull over because I almost crashed due to the abrupt shift. Once pulled over I tried to restart the car but once off and back on it wouldn’t allow me to shift or drive it. The steering wheel and brake remained locked. It has happened several times over the past week.

After heavy rain the backseat of the car was flooded as well as the rear wheel well likely due to the sunroof not draining properly. This led to electrical failure of the sunroof mechanism and potential to damage other electrical elements. This will be looked at by the dealership but have read that this is a known issue.

2020 GMC Terrain SLE Elevation Package 83,000 miles and needs complete engine rebuild @ cost of $10,700 per Dealership Service. Was told “I drove the vehicle with low oil” which Inturn is the cause of needing engine rebuilt. I have had this vehicle serviced, oil changed regularly etc NOT ONE TIME has the oil pressure/low engine oil nor anything related to oil illuminated on my dash. CEL yes after it apparently was too late and damage was done which showed code P06DD And P0324 through OnStar Diagnostics. There are also other complaints with same issue, and no notification of oil /oil pressure issues with relatively low mileage that have led to engine rebuild. I still owe on this vehicle through GM Financial, and a $10,200 engine rebuild on top of that… Not what I would expect out of GMC~

Radio goes from normal volume to as loud as possible while just driving.scares ya to death! Can't turn volume down with out 1st shutting off radio and turning it back on.dealship stayed there isn't a problem they could find.Blu tooth cuts in and out and locks the radio up untill you shut vehicle off and restart.shows you still on a call even though you have disconnected phone from radio.volume issue has happened several times

Dash had gone black intermittently, did not know what speed I was going. OnStar called oor phone multiple to notify us that our airbags we're offline for ten days no warning light on dash until one to two days later . Took to service was informed that gear shift control, engine control module, passenger presence module and airbag sensor needed replaced. All within a month of purchase of said USED vehicle. Vixed under warranty. Then another monther later, got warning on dash saying "conditions not current for shifting", park break light came on, and a p in a yellow circle with a wrench under it came on. Serive did fix vehicle, but could not verify message on dash about conditions not favorable... Also recalibrated breaker. Complained numerous times to dealer about these issues and was told "live with it".

Infotainment system shuts off completely. Disables blinker. Bluetooth and USB ports continuously went in and out and wouldn’t stay connected. Took to dealership on 02/07/2022 and was advised the system needed an update and the USB port needed to be replaced. USB port was replaced and software bulletin #20-NA-171 was applied. I picked up my vehicle on 02/08/2022 and the infotainment issue has not been corrected. It turned off again. USB ports seem to be working as they should for now. Also an issue with rear camera. Camera view sometimes shows a fisheye lens instead of normal camera view. Rear camera will sometimes stay on once car is in drive for a few seconds. I also notice a noise and vibration within my gas pedal randomly while driving. Clearly there are multiple issues that GM needs to acknowledge. It’s not a coincidence that this is happening to multiple people.

This 2020 GMC Terrain has a "feature" called autostop. This is not a switch to turn this off. It would not be so bad if the engine would run for 5 minutes at a stoplight before stopping the engine but it immediately shuts down the engine after a stop. This is getting annoying and dangerous due to the delay in getting the car moving. I have only had the car for a month. I understand that later gmc cars have a disable switch. This car should be recalled and either disable the auto stop permanently or be able to disable the "feature" on demand. Problem: potential crash hazard due to car not starting and damage to battery and starter.

While driving instrumental panel and infotainment panel completely blacked out for no reason at all. This is the second time in two days this has happened.

Instrument panel and infotainment system panel completely blacked out while driving vehicle

On fairly level ground, reduce speed hill descent control msg has activated (12 mile and maxwell area 2x, Rochester Hills Kohls parking lot exit) and once entering river bend dr. vehicle has also has had activated brakes on oak hill street in rochester. the vehicle has less than 4100 miles. very concerning about activated brakes.

WHILE STARTING VEHICLE THE INFOTAINMENT SCREEN WENT BLACK AND NOTHING WOULD WORK. STAYED THIS WAY WHILE DRIVING. STOPPED TURNED OFF CAR AND STILL DIDNT WORK. WAS TOLD IT WAS THE DATA COMMUNICATIONS MODULE.

Mileage: 4,200

TWICE WITHIN THE LAST TWO MONTHS MY ENTIRE RADIO SHUT OFF, MY SCREEN WENT BLACK AND SO DID MY GAUGES FOR AT LEAST 20 SECONDS. THEN THEY JUST CAME BACK ON AND PICKED UP WHERE IT LEFT OFF.

Mileage: 5,600

WE DROVE TO A FARM WITH A FAMILY OF 5M KIDS AND AN ELDERLY, AND PARKED MY CAR FOR 2-3 HOURS IN THE FARM'S OPEN AREA PARKING LOT. VEHICLE SHOWED NO WARNING LIGHTS, NO PROBLEMS, NO ISSUES DURING OUR DRIVE TO THE FARM AND PRIOR TO THIS TRIP. EVERYTHING WAS FINE WHEN WE GO THERE AND PARKED. WE WERE READY TO LEAVE THE FARM TO DRIVE BACK HOME, BUT THE CAR SIMPLY WOULDN'T START.THE NEUTRAL GEAR DIDN'T WORK, I ATTEMPTED MANY TIMES IN 30 MINUTES TO START THE CAR, BUT IT DIDN'T START, CONTINUED MAKING THE SOUND OF ENGINE ATTEMPTING TO START BUT NOT SUCEEDING. 30 MINUTES LATER, I DECIDED TO GIVE IT ANOTHER TRY, I WAS AFRAID TO BURN DOWN THE STARTER AFTER ATTEMPTING SO MANY TIMES. IT SOUNDED TERRIBLE, SCREECHING METAL SOUND. ALL OF A SUDDEN, THE CAR STARTED. I LET IT RUN, AFRAID TO TURN IT OFF AGAIN. AFTER 15 MINUTES OF RUNNING, WHILE WE WERE WAITING FOR ROADSIDE ASSISTANCE TO ARRIVE, THE VEHICLE TURNED OFF AGAIN, ALL BY ITSELF. NO ONE WAS INSIDE THE CAR, WE WERE WAITING OUTSIDE WITH THE DRIVER DOOR WIDE OPEN. I CALLED ROADSIDE ASSISTANCE, WAITED 40 MINUTES TO GET A LIVE AGENT TO TALK TO. THE YELLOW ENGINE LIGHT IS ON. I TRIED TO LOOK IN THE MANUAL TO BE ABLE TO FIND ANYTHING REMOTELY CLOSE TO WHAT WAS HAPPENING. CAME UP WITH NOTHING. THIS WAS SO FAR THE TRICKIEST THING TO HAPPEN TO ME. I SCHEDULED AN APPOINTMENT TO TAKE THE CAR TO THE DEALERSHIP FOR DIAGNOSIS.