2018 GMC SIERRA 1500 Electrical System Problems

Odometer Fraud. The contact purchased a 2018 GMC Sierra 1500. The contact discovered that there was a mileage discrepancy after the purchase. The vehicle was a private sale. At the time of purchase, the vehicle mileage was 72,000. It was later discovered later that the mileage was 241,556.

Mileage: 241,556

2018 GMC Sierra SLT's electric power steering suddenly stopped working, I almost got killed this issue has been reported by other owners

The contact owns a 2018 GMC Sierra 1500. The contact stated that the battery had been replaced three times since 2018. The vehicle was taken to the dealer; however, the failure was not duplicated. The contact referenced an unknown recall; however, the VIN was not associated with the recall. In addition, the contact stated that the first battery was replaced a month after the vehicle was purchased, and the second battery was replaced three weeks after the first replacement. The contact stated that the third battery was replaced a day after the second battery replacement. The manufacturer was made aware of the failure and a case was filed. The contact was advised to contact the NHTSA Hotline to report the failure. The failure mileage was approximately 36,000.

Mileage: 36,000

I've had the vehicle service twice for the same incident power steering shut off in the middle of drive Vehicle shuts down almost smashed into a freeway wall. This has been to the dealership numerous times to fix it and they have not. We are in the tens of thousands of dollars in repair and still nothing is fixed I've had this vehicle for 5 years it's been In the shop for at least 3 I bought it with 30000 miles it only has 61000 on it right now The last repair lasted 10000 miles this repair only lasted 4000 I almost died and was left Is petrified.

Engine lifters failed. Heard ticking noise first day truck was purchased that gradually got louder but was told by gmc service shop it was normal to hear the ticking noise. Also when cruise control is on and you are decending a hill the rpms raise and you lose engine compression this will cause your speed to drop to around 20 mph and has happened nunerous times.. as well when making a turn sometimes or just driving the vehicle turns off while in motion and you have to coast to the side of the road and turn the key off and back on to start driving agsin.. the loss of power is a complete blackout no dash.. no engine nothing. As result of the lifter issue the engine also hard shifts in and out of slow gears.. I have not driven my truck in about a year and still owe 22k on it. The issues with this vehicle are the same as the recalled 6.3 v8 engines.

Apparently, GMC began using soy-based wire coatings approximately 10 years ago. The wiring harness on my vehicle has literally been eaten and destroyed by squirrels causing the entire electrical system to be compromised. Safety features have been especially affected including but not limited to air bags, windows being inoperable, door locks being stuck open or closed without a physical key, stabilitrak system arbitrarily shutting off, and windshield wipers working intermittently. Obviously, these are critical systems for the safe operation of this vehicle for the driver, passenger, and members of the public that share the roads. I have had the main harness repaired at a dealership (paid by insurance) but it remains an ongoing safety and financial issue. The dealership identified other portions of the electrical system still need repair and may further compromise safety. Not only were warning lights activated, approximately 10 in-dash messages were displayed warning of malfunction prior to dealership inspection and partial remediation.

My engine and all electrical components including power steering and power brakes and all dashboard electrical will fail while driving. It is becoming more frequent and has almost caused an accident on numerous occasions to the point of not being able to drive safely on the highway any longer so now I only stay on surface streets and can't use for any out of town work. I usually do all of my own vehicle maintenance not been able to diagnose the culprit. Unfortunately I'm not able to afford the dealership diagnostic prices but open to any type of inspection.

While driving my truck and making low speed turns the dashboard (including center console) cuts off, along with my power steering. The truck has also shut off completely making u-turns causing me to almost crash. This also happened while driving around 60mph on the freeway, the entire dashboard went out, loss of steering, and truck shut off, almost causing an accident. When it does happen, it will cut out in 1 second intervals and steering will work again for 2 seconds then cut out again for 1 second, this causing me to stall. There are no check engine lights, or service lights that stay on. However, I will get a message stating: You are memory setting 3 in the system (wording may be different). In some cases the stabilitrak light will come on, the park assist warning stating it shut off comes on dash, and trailer break. I have a full service AUL warranty and had vehicle checked at certified dealership and no codes were recorded. I replaced battery and the problem is still happening. This is unsafe and should be part of the previous recall as my symptoms are the same exact symptoms as the other 2018 recall.

My starter quit at 81,000 miles. It has always been a bit weak starting, but I have never had a starter go out on a vehicle at 81,000. I have replaced it, and the rebuilt starter is better than what was ever on this vehicle. I am also having problems with the transmission shuddering, shifting rough in low gear, and sometimes it reverses fast. Repair shops won't even touch the transmission. The dealership stated they couldn't get the problem to replicate the issues even though they know there are issues with the 8 speed transmissions.

On February 10, 2025 the vehicle, a 2018 GMC Sierra, caught on fire while parked in the driveway of my home. The vehicle had last been driven earlier in the day with a return to home at approximately 12:45pm. At approximately 7pm I heard a loud pop outside of my home and saw orange light coming through the front windows. Upon going outside, I found the rear of the vehicle engulfed in flames. The fire was coming out around the remains of the license plate, up and around the rear bumper on the left side, and progressing up the tailgate and window hatch on the bed cap. The fire progressed forward over the next few minutes as the fiberglass cap burned. Eventually the fire penetrated the front window of the cap and rear window of the cab and began burning the interior of the cab. About the time the fire department arrived the fuel tank ruptured and began spilling gasoline onto the ground beneath the vehicle. The fuel tank was approximately 7/8 full. The fire department eventually extinguished the fire, but the vehicle was a total loss. My wife and I had been in close vicinity of the vehicle during the afternoon hours and had noticed nothing unusual. There had been no unusual issues with the vehicle during the prior drive, which had been a 5 minute drive to/from a local home supply store. There was collateral damage to the front of my house as a result of the heat from the fire, as well as damage to the driveway. If the vehicle had been parked in the garage it is resonable to assume that the house would have been destroyed.

The contact owns a 2018 GMC Sierra 1500. The contact stated that while driving on the highway at various speeds, the vehicle occasionally shuts off. The contact stated that several unknown warning lights were illuminated. The contact stated that the vehicle was pulled over to the side of the road and restarted. The contact was able to continue driving. The vehicle was taken to a local dealer and was diagnosed; however, the cause of the failure was not found. The contact was informed to take the vehicle back to the dealer if the failure returned. The manufacturer was notified of the failure. The approximate failure mileage was 128,000.

Mileage: 128,000

Electrical system turns off power steering while driving Dashboard lights up like a Christmas tree service track service brake stability Had this service back in 2022 August the problems have resurfaced there are no recalls have spent lots of money and still failing Spent almost a year at the dealership fast forward to years later the same problem is occurring I am running out of money

Noted the rear sliding window did not work. Upon further research and investigation found fuse 2 in the drivers side fuse box popped. Replaced the fuse and did not solve the problem. Further investigation found the harness that controls the rear sliding window and other items was sheared (all 3 wires cut in half). The harness is routed from the inside of the center console, through the drivers side hinge (pinch point where it cut the harness, and to the backside of the center console. Spliced the wires and reconnected confirming the fix to the problem. This issue poses a fire hazard. Recommend a recall to reroute the harness or a form of corrugation to better protect the harness and prevent further issues.

Part # 23337305 OEM Towing Control Module failure. replaced with factory part and unit failed within 60 days.

Rear sliding window defogger started smoking, filling the cab with smoke

The brakes sometimes lock up after use, or don’t disengage ( on one side) and the truck swerves ( steering wheel turns to the right ) into the next lane. I have to over correct and you can hear the brakes squeal. I will have to get off the freeway or the road. I am on trying to track off a couple of times for 5 to 10 minutes Until it stops doing it. It does it on average once to Twice a day. Was told could be brake calipers hoses, speed sensors sending the wrong information to the ABS system. It is very dangerous to drive the truck on the freeway doing 75 miles an hour!

I purchased my Sierra in 2021 and 2 weeks after purchase I got a warning for service stabilitrk and another for trailer brake system. This is very very annoying and also has my abs light on. My next issue is a code u510 for active grille shutter assembly. Please fix these issues as they are very common and unsafe. Not to mention as much ad I paid for this truck.

Transmission started to shutter at 24000 miles. Dealer said couldn’t find anything. ABS and Stabilitrack light came on at about 40,000 miles off and on. Both these problems could result in a crash. On freeway or streets. The display information/ radio has a mind of its own. Connects to any phone number or start the on star call and etc. it takes your attention off the road and can result in a crash.

I kept getting a constant alert on my vehicle dash board that said "service trailer brake system" the beeping alert was quite literally constant and it covered up the digital speed odometer, every time I tried to acknowledge the alert it would just pop up and start beeping again. I searched online and quickly realized that this problem with the brake system has plagued GM vehicles for several years and I attempted to fix the issue myself by buying factory parts that other GM owners stated was the issue but it did not correct the issue. I ended up needing to take it to a GM service center and my vehicle was there for 2 business days and it ran me several hundred dollars to have GM fix the issue in the electrical brake system. Again according from online research this problem has plagued a large number of GM vehicles and it would be nice to see GM issue a recall and correct the issue so other people don't end up in the situation I was in.

Have experience increased brake pedal effort, hard brake pedal, and/or potentially increased. stopping distance. The condition is more prevalent at low speed when softly applying the brakes. The Driver’s Information Center, (DIC) “Service brake assist” alert will activate. Extreme safety risk to myself and my children. Bulletin N182202780 & NT192268490 needs to be tied to this specific VIN Number as well.

The electric power steering failed while accelerating into a turn from a stop at an intersection. The wheel was jerked from my hands, and the engine stalled, all electrical failed momentarily. Within a couple of seconds everything returned to normal. This has happened several times since I purchased this vehicle. Also the electrical power steering drops out quite often at low speeds, such as in parking lots. No warnings have ever been given. In May of 2021 the dealer replaced the steering rack, the problem has continued intermittently to this date. I have researched for recalls on this problem and found that GMC issued a recall for years 2014-2017, and am amazed that they could just declare the problem fixed, and leave such a dangerous problem unresolved!

Loss of dash electrical system and service stabillitrac warning came on when power was restored along with service suspension warning light. Headlights flicker and engine starts powering down before power comes back on by itself. If fuse to suspension is pulled or negative is removed and replaced, all warning lights go away.

Break system is making scratching noises as if it is a caliber breaking problem or a caliber piston problem, it is also setting off the trailer breaking system light on the dash as well as the trail traction control light.

The main harness under the truck , front to back . There was a separation from the conduit, wires exposed and were arcing. Truck would not start . I have since had it fixed . I just feel truck is not that old , to soon for a problem like this . And it cost a lot of money.

I purchased my 2018 GMC Sierra 1500 pickup truck new in 2018. To date it only has 28K miles on it. I have never used the trailer breaking system that it came equipped with. On 12/24/22 we were traveling to a family function for Christmas. The "service trailer break system" warning message came on and the chime chimed continuously until I got to my destination, about an hour away. This chime was very distracting and there was no way to turn it off. After arriving at my destination I turned the truck off hoping it was just a fluke. When I started the truck back up the "service trailer break system" warning light and chime continued. It continued for an hour on my way home. Again, this was very distracting and I was unable to focus 100% of my attention on the road and my driving. Thank fully I made it home okay. On 12/27/22 I took the truck to my mechanic to have him take a look. He said he has heard of this issue with these pickups. His diagnostic confirmed that the trailer breaking switch (on the dash) was functioning properly but said that the chassis control module was likely the culprit. He replaced the control module and it had to be programed by a factory technician. After this part was replaced the warning light or chime does not come on anymore. I have the defective part for inspection and the bill totaling $1191.86 for the repair upon request.

While driving 35 miles per hour in the early morning hours I came to a 4-way intersection and applied the brakes slowly. Suddenly, I lost all power in the brakes and the steering wheel locked up. The lights, and stereo remained on, and my dash board display immediately showed a red check engine light. I immediately turn on my hazard lights, turned the ignition key off and tried to restart the truck. There was no clicking sounds. The truck would not start but the lights dimmed and the dash display now showed an intermittent yellow, flickering check engine light. After roughly 30 minutes while waiting for AAA to arrive I tried the ignition key and the truck started up with a red check engine light. Rather than attempting to drive I had AAA tow my vehicle to the Chevrolet dealership where I purchased the truck.

The light in the dashboard gose dark and it gives me a warning collision alert and the tiers they spin out of control when turning or when I I’m driving I think it’s the tiers they have a lot of tread still…

Informant system and instrument clust/panel starts to change with nothing be clicked. Starts to phantom change everything which is deters from paying attention to actual driving becoming a safety hazard. Dealership has tried to update the software and still does not work.

I was stopped at a fast food drive thru and then I tried to go to the next window and the truck wouldn’t move at all it will just rev so I put it in parked turned off the truck and turn it back on put it on drive and was able to move for like 40 ft then it did it again so I had it towed to my home

Trailer brake modulator on 2018 GMC Sierra does not consistently signal trail brakes to work when needed on our 7,500 pound RV trailer. GMC dealer eventually found that the battery cables were undersized as installed with the factory towing package on the 2018 GMC Sierra. The undersized battery cables do not consistently deliver adequate voltage to the trailer brake modulator on the GMC Sierra, so inconsistent electric brake function for our 7,500 pound RV trailer. Dealer had difficulty diagnosing the problem as being the wrong factory-installed battery cables to go with the factory-installed trailer towing package. So it cost us $1,600 to have the GMC dealer correct a problem caused by the GMC factory installing undersized battery cables. Fortunately, this did not result in a collision for us, but it might for someone else. Our 2018 GMC Sierra kept sending vague, randomly timed warnings to the dashboard to "Check Trailer Wiring." Very frightening, dangerous and costly (for us) mistake by GMC. Will the brakes work this time, or fail on the way home? Problem started in 2021 RV season, but took awhile for us to recognize the need to take to the GMC dealer for them to diagnose base cause. Took time for us to experiment changing trailer wiring connector on bumper and trailer brake control on the dash. Work for awhile, then fail. Work for awhile, then fail. Arrrrgh! Ask GMC to put more adequate battery cables on ALL their vehicles, please.

SERVICE TRAILER BRAKE SYSTEM - warning

“Service- trailer brake system” light keeps coming on. It is super repetitive. It comes on about every 30 seconds. It’s a loud beep that lasts quite a few seconds. Eventually, the beeping did not stop until the truck was stopped. Truck was just bought yesterday. Happens at any speed, even when stopped.

Im getting a service trailer brake system soon message on dash.

The contact owns a 2018 GMC Sierra 1500. The contact stated while driving approximately 70 MPH, the trailer wiring harness system warning message was illuminated. The vehicle was taken to a local dealer where it was diagnosed with needing the wiring harness replaced; however, the vehicle was not repaired. The manufacturer was not informed of the failure. The failure mileage was approximately 77,000.

Mileage: 77,000

At 50,000 miles the "service trailer brake system" error message appears constantly due to factory defects and its very common. These trucks should be recalled everyone is in danger on the roads and its a very common problem. I have not taken it to the dealer because i should not have to pay for this very common problem, it should be recalled.

The truck displayed warning lights for ABS, traction control, trailer brakes, and front park assist. Additionally speed control (cruise) did not function. This presented a safety issue. I took to dealer asap. They repaired by replacing left rear wheel speed sensor. Cost about $216. Appears to work correctly at this time.

BATTERY DIES AFTER 5DAYS OF NOT BEING DRIVEN. BATTERY CONTINUES TO GO DEAD, DEALER STATES NOTHING IS WRONG. NO REPAIRS WERE MADE. STRANDED 5 TIMES WITH A DEAD BATTERY

Check engine came on and says manufacture specific issues/codes. Safety restrain system. P10e4

THE FIRST THING THAT HAPPENED WAS THAT ALL OF THE ELECTRICAL SYSTEMS ON MY TRUCK WENT OUT AND MY TRUCK WOULD NOT START. IT FINALLY STARTED BUT IT WOULD NOT MOVE FINALLY IT WOULD MOVE BUT VERY SLOWLY THIS HAPPENED ON 11/20/2019 I HAVE DOCUMENTATION THROUGH ONSTAR FOR THIS INCIDENT. MY BRAKES STARTED SLIPPING ON 07/01/2020 AND STILL DO NOT WORK PROPERLY. MY TRANSMISSION HAS NEVER SHIFTED CORRECTLY. WHEN I ACCELERATE OR WHEN I SLOW DOWN THERE IS A SHUDDER AND A JERKING SOUND. AFTER SITTING FOR A WHILE WHEN MY TRUCK IS PUT IN REVERSE IT HESITATES AND THEN SEEMS TO JUMP INTO GEAR.

Mileage: 27,000

MY TRUCK LOCKED ITSELF WITH THE ENGINE RUNNING WHEN I WAS PARKED IN THE DRIVEWAY. ALSO HAVE HAD THE BACK DRIVER SIDE WINDOW ROLL ITSELF DOWN PART WAYS WITHOUT ME INITIATING IT. ANOTHER OCCASION I PUT THE TRUCK IN GEAR TO DRIVE POSITION AND THE BRAKE OR SOMETHING HAD IT LOCKED PREVENTING ME FROM MOVING EITHER DIRECTION IE; DRIVE OR REVERSE. WAS THEN PARKED IN HOME GARAGE AND ATTEMPTING TO BACK OUT.

Mileage: 12,000

MY VEHICLE IS HACKED ANYTIME I AM DRIVING THE VEHICLE I AM NOT IN FULL CONTROL. THE VEHICLE STEERS ITSELF LEFT OR RIGHT WHILE DRIVING, THE BRAKES ARE ALWAYS ON WHILE DRIVING SOMETIMES BRAKING HARDER BUT ALWAYS ON. THE INFOTAINMENT SYSTEM HAS MANY GLITCHES. THIS VEHICLE HAS BEEN BACK TO THE DEALERSHIP MORE THAN 15 TIMES HAS BEEN OUT OF SERVICE OVER 35 DAYS GM EVEN FLEW A ENGINEER/TECH TO INSPECT THE VEHICLE AND SAYS THEY COULDNT FIND ANYTHING. THEREFORE THIS VEHICLE IS HACKED THERE ARE SO MANY ISSUES AND GLITCHES AND THE FACT THAT THE TRUCK ONLY ACTS LIKE THIS WHEN I AM DRIVING NO ONE ELSE. LIKE IT CAN BE TURNED ON AND OFF INSTANTLY. I HAVE TONS OF VIDEOS PICTURES AND SUPPORTING DOCUMENTS BACKING THIS. I NEED HELP THIS IS A SERIOUS ISSUE AND THERE IS SO MUCH MORE TO IT THAN I CAN TYPE HERE SOMEONE PLEASE GET AHOLD OF ME TO HELP OR POINT ME IN THE RIGHT DIRECTION. THIS VEHICLE WILL BE RETURNED TO GM SOON AS THEY ARE DOING A VEHICLE REPLACMENT PER ALL THE ISSUES BUT THIS NEEDS FURTHER ATTENTION BECAUSE IF THIS CAN HAPPEN TO ME IT CAN HAPPEN TO ANYONE . PLEASE HELP

Mileage: 200