2020 GMC Sierra 1500: water leaks into the cabin

Filed Jun 18, 2025 · Visibility · CA

The rear back glass is leaking water excessively in to the inside of the vehicle when it rains or gets washed. The vehicle is available at any time for inspection. The amount of condensation that accumulates on all the interior windows makes it impossible to see out of the vehicle. The defrost can not handle the amount of moisture build up. The Dealer knows about this condition and it has been verified by a window company. The manufacture knows and understands there is a problem and has put out a Technical Service Bulletin ( TSB 18‑NA‑383 ) for this issue but will not cover the repairs. GM knows that every single vehicle with this window designs from 2019-20121 will leak just outside the 3 year 36k mile warranty coverage. The cost of repair is approximately $2k. Dealer will not cover repair.

Filed Apr 22, 2025 · Body · FL

Had water leaking into cab of truck. First incident they stated it was a rear window seal and it was "repaired" under warranty. Second incident I was advised it was body panel separation where the cab roof and side body seam was leaking. It was repaired by sealing with "body seam sealer." I later read these repairs should have been welded. This was after the warranty expired and I had to pay for it. I then read on the Silverado/Sierra forum this repair should have been a weld not just "glued" is this a safety issue?

Filed Feb 1, 2025 · TX

Water entering from the rear window causing rear seats and roof hard cover to get wet and cause a wet odor (humid). 2020 GMC 1500 AT4

Filed May 1, 2024 · Body, Electrical · CA

The rear sliding window leaks water inside the cab every time it rains. With water getting into the cab the issue of mold has begun and that could be a serious factor to any children or adults that ride inside the cab of the truck. There is also rust issues that are notable under the rear seats of the vehicle. Water inside the cab can also interact negatively with any electrical components of the vehicle. I tried to get ahold of the dealer and they always say they don't have time to get my truck in. I have read that this has happened to other vehicles that are the same year and model and they just fix it with caulk which does not seem appropriate for a almost new vehicle. The vehicle has not been inspected. There were no warning lamps prior to this issue. A possible symptom was that my back up camera stopped working for a day right after a rain.

Filed Apr 1, 2024 · Body · CO

GM refuses to fix a known design flaw in the back sliding glass frame on 2020_24 gmc sierra trucks. This issue will generate toxic mold as large quantities of water enter the cabin and can be extremely harmful for certain individuals allergic to mold. GM knows about this issue and tried to secretly advise techs via TSB 18-na-383 to apply sealant on the frame and if customer returns to replace frame. However they do not want to do this outside the 3 year warranty. The back glass on a truck is not a serviceable item.

Filed Feb 19, 2024 · Body · MN

Rear Sliding Glass window frame has cracked and allows water to enter the cab of the vehicle. Yes this is available for inspection. The water entering the cab of the vehicle can create mold from moisture build up if left untreated. I was able to have the dealer service center confirm the issue noted in [XXX] but they were unable to repair it as it is outside of warranty. I was able to have an independent 3rd party glass company confirm that it was indeed a manufacturers defect with a cracked housing and not an issue with sealant around the glass itself. No warning lamps or other indications other than water in the back seat of the vehicle. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Sep 24, 2023 · Visibility · WV

The rear window on this vehicle is leaking water and has been for some time. It has become quite bad and is causing an odor and discoloration in the carpet. I could not find the cause of the problem until recently with the plastic cracking more. The vehicle has 41,000 miles and the dealer stated that is out of warranty and all repairs would be a cost to me. I researched this and have found it is a common fault this this vehicle.