10.0

really awful
Crashes / Fires:
1 / 0
Injuries / Deaths:
0 / 0
Average Mileage:
0 miles

About These NHTSA Complaints:

This data is from the NHTSA — the US gov't agency tasked with vehicle safety. Complaints are spread across multiple & redundant categories, & are not organized by problem.

So how do you find out what problems are occurring? For this NHTSA complaint data, the only way is to read through the comments below. Any duplicates or errors? It's not us.

2020 GMC Sierra 3500 brakes problems

brakes problem

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2020 GMC Sierra 3500 Owner Comments

problem #6

Jul 012024

Sierra 3500

  • miles

A D V E R T I S E M E N T S

driving approximately 50 mph when vehicle suddenly made loud bang and locked up rear brakes for 25' coming to a stop in road side ditch, numerous vehicles had to make evasive actions to avoid me and other vehicles. flat spotted tire abut no visible physical damage. sat on side of road for transmission temp to cool down then drove to shop without repeat. called dealer was told the earliest appt was a month away. have not been able to repeat incident so far. this has happened a few times and is becoming more frequent, mfg has tsb issued but indicates they cant assist because my warranty has expired so i will have to pay 225 per hour diagnostic fee. this is untenable and dangerous. this needs a recall and repair ASAP.

- Atlantic, IA, USA

problem #5

Jan 152023

Sierra 3500

  • miles
Rear tires locking up out of no where almost made me jack knife.

- Dalbo, MN, USA

problem #4

Jul 072020

Sierra 3500 4WD 8-cyl Diesel

  • Automatic transmission
  • miles
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.

- Irving, TX, USA

problem #3

May 222020

Sierra 3500 4WD 8-cyl Diesel

  • Automatic transmission
  • miles

A D V E R T I S E M E N T S

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.

- Irving, TX, USA

problem #2

May 012020

Sierra 3500 4WD 8-cyl Diesel

  • Automatic transmission
  • miles
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.

- Irving, TX, USA

problem #1

Apr 152021

Sierra 3500

  • miles
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.

- Irving, TX, USA

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