Brand new Trailblazer RS - 2022. When you open any door of the vehicle (engine off) there is what can best be described as a loud buzz, humming noise (perhaps a "motor" starting) from rear end. Lasts about 5 seconds. You can close the door, open it (or any door) again and it does not happen again. You can try it 30 minutes later and it does not happen again. But after it sits for a longer period of time it does happen again. What is this noise? Quite loud and noticeable. A problem? The odd part too is that it is from rear of vehicle, not engine compartment.

 

Can you help by checking where the noise appears loudest ?

 

I will try to pay close attention after car sits a while and I can recreate noise. It is DEFINITELY in the rear of car. i'll try to pinpoint if on one side or the other.

 

I have a 2022 trailblazer as well with the exact same problem. I am going to ask the dealership when I take it in for my first oil change.

 

I found another unusual thing about the noise. Yes it happens when you open any door or tailgate after the car has been sitting for a while. BUT I don't know if you use or are familiar with the "mychevrolet" app. It gives you the ability to remote start your car or to check things on your car like tire pressure, and more. I decided to try it. I stood next to the car. Opened the app. Screen appears allowing you the option to start, lock doors, etc. I did NOT select any of those options. I selected one called Vehicle Status (tire pressure, fuel, etc.). The moment I did it....THE LOUD NOISE from the car. Same as when you open any door, etc.
Many have posted they believe the noise is a fuel pump. Some say computer. It seems the fuel pump would not be engaged when you are just checking tire pressure, so perhaps it is the computer starting. All I know is this is my only and my MAJOR complaint about the TB. It is 2022. Cars are made for decades with fuel pumps and computers. They couldn't come up with a more normal design for the TB?
PLEASE let us know what your dealer says. My dealer simply gave me "yeah, some of them do that".