Hello - 2012 Suburban with 145k miles has a rattle on the furthest back rear window. It's the window in the trunk/3rd row area that does not open. My hypothesis is something is rattling up against the glass and then reverberating. Like if something was tapping against it. I've been in the back while my wife was driving and pushed and pulled on everything could think of to see if could isolate the sound and to no avail can't identify what it is. This is not the side that has the jack/storage compartment.

Any ideas?My next guess is need to take off the interior panel, but that is not something I frankly want to do.

 

Check under the car as well, maybe something loose hitting bottom of body

 

There's really not much in there that could rattle against the window. It's pretty easy to pull the trim off around the window. There's just a couple of fasteners on the pillar trim, the other trim pieces just pop off.

 

Hello, i am having this same issue, did you ever find the cause? Any fix?