2020 GMC Sierra 3500 Electrical Problems

Vehicle will not start due to known GM issues. This failure left my family stranded in cold dark unsafe area once already. If we were in the flow of traffic or had to leave an area immediately we would have been unable too. Known GM issue, engine fault code P12A6 fault code. Bulletin: PIP5719A discusses this issue. I am being told by the dealer there is a newer bulletin which advises ECM update. GM dealer is stating ECM software upgrade is required to resolve at owners expense. Owner is responsible for diagnostic fee in addition to repair costs. If the issue is not resolved vehicle may continue to experience starting failure and or other electrical problems. The night the vehicle left us stranded instrumentation was erratic and not reading properly on the instrument cluster. Very unsafe and GM should reach out to customers to inform them a software update is needed and it should not be at the expense to the consumer if the consumer is out of the bumper to bumper warranty.

NHTSA ID

11570194

Incident

Jan 21, 2024

Plugged in engine block heater and the car erupted in flames. Total loss.

NHTSA ID

11493546

Incident

Nov 13, 2022

The component that failed was the passenger side or main battery. Our safety was compromised when the design of the HVAC system and the battery location allowed the hydrogen sulfide gas into the passenger compartment of the vehicle. The issue has not been confirmed by a deal or independent service center. The battery(s) and vehicle are available for inspection to confirm the issue. I have uploaded pictures of the battery and one can visually see the swollen battery with liquid leaking out of it. There were no warning messages or other symptoms prior to the failure. The rotten egg smell started shortly after the truck was started and my three young children were in the truck for about 10-15 minutes while I was loading items in the bed of the truck. When I entered the vehicle, the smell was extremely strong and my eyes started burning. I opened all the windows to air out the passenger compartment and thought it was possible off gassing from the nearby septic field. Once driving with the windows now closed, the smell came back instantly and very strong. My children started complaining of headache and nausea. For the next part of the trip, we drove with the windows down. When we arrived at our destination, I was able to determine the smell was coming out of the HVAC system while in normal "Auto" mode. Opening the hood, I went to smell around the engine compartment and when I got over the passenger side main battery, the rotten egg smell was so strong that my nose and eyes instantly started burning. We then drove the truck home with the windows closed and the HVAC system in recirculate but the smell still entered the passenger compartment. All four of us had symptoms of hydrogen sulfide poisoning with my son being the worse with multiple vomiting episodes immediately upon exiting the vehicle. Poison Control was notified and all four of us were evaluated in our local Emergency Department for Inhalation Toxin. The truck is all OEM.

NHTSA ID

11471359

Incident

Jun 26, 2022

Infotainment system AND center instrument cluster went completely black - six times over the course of one month. I took the truck to Alan Webb Chevrolet in Vancouver Washington. Their service technician was aware of infotainment system “Black Screen of Death - BSD” problems due to previous repair work on several different GM models. However, on the way to their Service Department to get this fixed, I rolled down the driver’s side window about 6 inches to get some fresh air and rolled it back up. Out of nowhere the Infotainment system AND the center instrument cluster came back to life. No rhyme, no reason and both stayed on (illuminated). Their Service Technician could NOT recreate the BSD. They had my truck for more than one week AND said they were working with GM engineers to resolve this issue. GM case number SR 9-7065134382. I’m driving and towing my 5th wheel blind without a remedy for this electrical issue.

NHTSA ID

11440826

Incident

Nov 3, 2021

The computer lights up the dash reducing power and turning off power to trailer brakes. This has almost caused an accident on several occasions . It happens a couple of times per trips. This vehicle has been in the shop a couple of times per month since it was put into service. Glenn Polk Chevrolet has worked on it each time and the problem is still there. This truck has also had several injector issues. There is an open case with this vehicle with General Motors with no resolution. I have filled out forms on each of my 2020 GMC's 3500's.

NHTSA ID

11418621

Incident

Jul 7, 2020

The computer lights up dash reducing power and taking the trailer brakes away. This almost caused a wreck when the truck shut off and the brakes failed. This truck has been in the shop at least once per month trying to fix the issues, from computer and brake failure to injector failure. Glenn Polk Chevrolet in Sanger has been working on this since the truck was new. Also we have case open with General Motors without resolution. The dash lights up at the same time as the brakes fail.

NHTSA ID

11418617

Incident

May 22, 2020

The computer lite up the dash and reduced power, plus took the trailer brakes off line. This happened while loaded. To reset the system you have to pull over and turn the vehicle off. This happens 2-3 times per day. This was a problem at 600 miles. The transmission shifted from 10 gear to 5th gear while driving 75 miles per hour. The truck had 75,000 miles on it . Had to send another truck out to pick up the load in Santa Rosa New Mexico. The dealer Glenn Polk in Sanger has been working on for the last 4 months There is never a warning until the lights come on with a system failure.

NHTSA ID

11418595

Incident

May 1, 2020

The computer malfunctions. It is available for inspection. The computer lights up and causes failure in the trailer brakes. Glenn Polk the dealership in Sanger Texas has been working on a fix but has yet to come up with one. I have spoken with General Motors Representatives several time trying to resolve the problem without result. I also emailed the CEO last Friday and have heard nothing. There were no warning lights until seconds before failure.

NHTSA ID

11418543

Incident

Apr 15, 2021

PROGRESSIVE PAUSE STARTS WHEN STARTING VEHICLE. AFTER A FEW WEEKS OF PAUSE STARTING VEHICLE HAD NO POWER AT ALL. TOWED IT TO DEALER THEY REPLACED A BAD BATTERY. PAUSE START CONTINUED AND AFTER 4-5 WEEKS VEHICLE WOULD NOT START. COULDN'T TURN PARK BREAK OFF. THERE WAS POWER (LIGHTS IN DASH CAME ONE) BUT DIDN'T START. VEHICLE PARKED AND ONLY AFTER SITTING UNUSED THIS HAPPENED BOTH TIMES. (1ST TIME NO START, HADN'T DRIVEN FOR 3 DAYS, END OF SUMMER WEATHER) (2ND NO START, SAT OVERNIGHT COOL WEATHER, BUT NO FREEZING. TOWED TO DEALER AND THEY FOUND NOTHING WRONG.

NHTSA ID

11375790

Incident

Sep 28, 2020