Rear Window Leak and GM warranty warning

bowtie2007 · March 18, 2022

The rear sliding glass window of my 2020 GMC Sierra 2500 developed a leak in January of 2021. It caused water to saturate the carpet under the rear seats and allowed water to enter the rear seatback storage compartments. TSB 18-NA-383 states the cause is from cracks developing in the rear sliding window plastic upper rail glass guide and the solution instructs dealers to put seam sealant over the cracks. Skip forward a year later and 3,000 miles out of factory warranty. The sealant failed and the window was leaking again. GM initially refused to pay anything and the dealer wanted $1,382.70 because they stated I needed a full rear window replacement. Extended warranty wouldn't cover it because it was not a mechanical breakdown. After a many calls to GM customer assistance, they agreed to cover 70% leaving me to still pay $414. This window leak is not isolated to just a few. I had a 2019 GMC Sierra 1500 in which the rear window leaked before I traded. A friend of mine has a 2020 GMC Sierra 2500 and his window is leaking. There are hundreds of pages of forums in the 1500 forums regarding a leaking rear window.

GM will try to put a bandage on the window cracks in the form of sealant instead of actually replacing the defective window. Many of the people in the forums report that the sealant does not last as was the case with mine. If you are unlucky enough to fall outside of warranty when the sealant fails, GM will not cover anything without a fight.

sheath · March 18, 2022

Depending on the ambient environment this leak could result in black mold, creating an unsafe environment inside the vehicle (who wants to strap their child into a seat right above a black mold infected carpet). If that issue exists a complaint can be filed with the NHTSA, as per their website.

How to report a vehicle safety problem with NHTSA

Had a situation with a Honda Motorcycle. Honda absolutely refused to look at it. There was a rather large response in filing reports from owners of that bike due to a web forum. NHTSA got involved, and Honda finally worked to resolve including bikes no longer in warranty, and even bikes sold to another owner. I came into towards the end, so I don't know how long it took, but it was impressive to see a collective group being able to get something done.

Hope this helps.

Edited March 18, 2022 by sheath

tbully · March 18, 2022

It's funny how I got laughed at when I started questioning a class action. The basis of my reasoning was exactly this. Vehicles that are fairly new but out of warranty (due to the normal high miles/usage of these vehicles). GM's "sealant fix" is/was a gamble to get a majority of these vehicle beyond warranty where they'll just tell the owner to pound sand.

....and here we are....

GM knows this is a huge problem and their response is "caulk". Still pisses me off.

That said, my replacement window - which I had to fight for - (and sealant) has held for the past year and ~4,000 miles. (We don't drive much.)

Good luck to you and sorry you had to go through this (again).

bowtie2007 · March 18, 2022

I did not think about NHTSA but I have filed a complaint with the BBB and FTC claiming a violation of the written warranty. I don't know how they can have a cracked window frame and just put sealant over the cracks instead of a replacement part. I don't know anything about how class actions lawsuits work or I may have tried that. tbully, I'm glad you got the replacement window instead of the sealant!

B W J · December 3, 2023

I am having the same problem with my GMC Sierra- 2500 crew cab. I just noticed the carpet wet 2 months ago when cleaning the truck. I thought maybe I had left the window open during a rain. So dried it out and the next rain we have a wet cab again! I hope GM handles this properly! I have been a loyal customer since 2001. This is my 5th truck with GMC.

BuckWallace · December 4, 2023

Pretty ridiculous that the TSB says the "fix" is seam sealant, then suddenly when it's out of warranty the dealer says the fix is a full replacement. Boy, I wonder why that is??

Edited December 4, 2023 by BuckWallace

Z714Mike · December 4, 2023

My 2020 Silverado 1500 at the dealer for the exact same thing and received the same response. We’ll see what happens when I contact GM??

ShotgunZ71 · December 9, 2023

As some have read in the other thread, I sealed mine myself. On a previous truck, I had a dealer do the repairs and I ended up redoing that hack job that kept leaking. This time, all was done by me. No, I'm not going to keep doing it if it comes back. I'll either have a solid glass put in or I'll just get rid of it.

jbrentjordan · February 1

What is the number for GM customer assistance?

carlos Ec · March 5

Im in the same situation, i am pretty sure mine started leaking probably long time ago by how much it leaks now, but i just noticed and now im out of the 3 yr bumper to bumper, GM ignore me the first couple times i called them, until i mentioned the TSB then my case escalated, that was 3 weeks ago and now its been a week and i havent heard from them and im unable to contact the lady i spoke with, it must be a way to get them to be responsable for this issue we are a lot of people involved in this problem, and a lot other bunch that has not yet find out about it, this are 50k to 70k trucks pretty much new leaking water, creating future problems as well like corrotion in wiring, paint damage, headliner damage, fungal etc.

Spikey · March 12

I use my 2020 Trail Boss truck for pulling my RV and I love this truck, just found out I was having this issue of leaking back window, I took it in to the dealership and found that my extended warranty doesn't cover water leaks or bad seals lol wtf (don't buy the ext warranty) it doeasn't cover ******. anyhow was told to fix this it would cost $1,265.00 so it has to be fixed so in the meantime I contacted GM they are looking into it and will tell me in a couple days what they can do for me I will post the results of this seeing how this is a manufacturer issue, my truck only has 17,600 miles on it.

GMCustomerService · March 18

On 3/5/2024 at 2:44 AM, carlos Ec said:

Im in the same situation, i am pretty sure mine started leaking probably long time ago by how much it leaks now, but i just noticed and now im out of the 3 yr bumper to bumper, GM ignore me the first couple times i called them, until i mentioned the TSB then my case escalated, that was 3 weeks ago and now its been a week and i havent heard from them and im unable to contact the lady i spoke with, it must be a way to get them to be responsable for this issue we are a lot of people involved in this problem, and a lot other bunch that has not yet find out about it, this are 50k to 70k trucks pretty much new leaking water, creating future problems as well like corrotion in wiring, paint damage, headliner damage, fungal etc.

This is certainly not what we like to hear, carlos Ec. Please know, customer satisfaction is extremely important to us. Our team would be more than happy to take a closer look into the concerns with your truck having a leak on the rear window. To do so, please send an email to [email protected] with ATTN: carlos Ec/GM Trucks in the subject line.

Please include your contact information, VIN, a brief description of your concern, and the name of your preferred dealership. We look forward to hearing from you. To learn more about GM’s Privacy Policy, please visit https://www.gm.com/privacy-statement.html. The information you provide may be monitored and recorded and is subject to the GM Privacy Statement.

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Spikey · April 6

Ok so GM stepped up and helped me out with my leaking back window they covered about 80% of the cost only costing me $300 so I'm happy with that.

ForkliftJeff · August 7

I'm having the same issue in my truck. First happened February 2022. Heard sizzling coming from behind the rear seats during rain and with the defroster on, turn defroster off and the sizzling stopped. Checked and sure enough the leak was coming in top right side of my rear window. Took it in under warranty and they resealed it. I got it back and there was urethane everywhere. It was on my paint, on the glass, and the spoiler. I had to take it back for them to clean it all up. Fast forward to now..... I'm getting that rainy day sizzle again. Called the dealer and I'm getting the well it's out of warranty now and you need a new rear window to fix it. I complained, having no faith in the previous repair seeing how the outside looked with sealant all over the place, and they have agreed to split the cost of the new window replacement 50/50. But that's still over $1000 so I'm not sure what to do. Was thinking about doing the reseal myself but not too sure yet.

ForkliftJeff · August 7

Just looked through my records. Turns out It was in once before in November 2021. Hmmmm, I think they should have replaced it while it was there the second time in February according to the TSB.