After getting the cracks in the rear window frame covered in seam sealant in January 2021, the window began leaking again in January of 2022. This time, my mileage was 39,000, therefore the dealer said it was not covered by the factory warranty and the cost was $1,382.70. Extended warranty would not cover the cost because it was not a mechanical failure. General Motors looked at the second leak as a separate issue even though their first repair was a bandage. The sealant covered the cracks so i could pay for a window outside of warranty. After a fight with GM customer service, they agreed to pay 70%. Why I still owe 30% on a botched warranty repair baffles me. The leaking window is not isolated. I have a friend with the same truck and his rear window is leaking. I traded a 2019 GMC Sierra 1500 for the 2500 and before the trade, the rear window was leaking. A quick online search of rear window leaks will provide hundreds of pages of complaints.

In January of 2021, there was a heavy rain. The top of the rear window leaked enough water to saturate the rear seats and carpet. There was even water in the rear seat back storage compartments. I brought the truck to the dealer and they repaired it following service bulletin 18-NA-383. The bulletin states that the cause is cracking in the rear sliding window plastic upper rail glass guide. The solution is to put Kent High-Tech Seam Sealer across the entire top of the glass, not actually replace the cracked window frame.