rattle making me nuts

[wizard4878]

rattle coming from the backseat,  no,  its not the headrest,  I took them (yes all 3) out and it made no difference.  If someone is sitting back there it dosent do it nearly as bad and sometimes not at all.  This makes me think the seat back is loose somewhere.  I did notice that there is a handle beside the headrest,  I didn't think that this folded down, but at this point I don't know.   
Anyone else have this issue and come up with a fix?

[bdallas]

I had a mystery rattle going on for a while... finally found out it was the rear seat belt latch that was rattling against the C pillar because the belt was twisted.

[Gangly]

Check the D rings of the rear seat seatback where the seatback slides into its retainer system.  I had to add electrical tape to the d ring because it wasn't a snug fit and was rattling in its attachment point.

[Z06JPB]

Depending on which trim level and options you have, there’s a bunch of stuff back there that can rattle:

 

 

[seamus2154]

I have a brand new 2021 Sierra Duramax.  I had the same thing a rattle in back seat area, seemed like near seat belt mounts. We tried everything to duplicate but would only do it on the highway at speed. Drove me crazy! Had my wife back there while driving , we were like crazy people trying to find it. THEN put my 12 year old back there and she narrowed it down to a body seam under the back seat near seat belt mount. But nothing was loose. I put the truck up on the lift and there was a heat sheild under the floor right near that spot on the passenger side. It was bent up on one corner and tapped and vibrated at highway speed!!! Sounded like it was clearly in the truck, but it was right under that spot underside of the vehicle. Good luck

[garymcel]

i also had a rattle that was driving me crazy i thought it was the back seat sounded like it was seat after a couple of months i found the rattle and it was not the back seat it was the dome light had fallen down some and that was making the noise i just had to push it back up till it snapped back in

 

[nichos]

If you have a sliding rear window, try sticking a towel between the cable guide thingy and the glass.

If that fixes it, here's a permanent solution that worked for me:

 

[wizard4878]

thanks for all the idea's,  but since mine won't do it if someone is sitting in the back seat I'm pretty sure it's not the window or a heat shield,  but I will definitely try both of those fixes anyway.  Hopefully one of these will work!   Thanks again...

[DNAK]

If it is coming from by the head area, I found it was the seat belt swivel in the rear pillar.  I put a 3/8 rubber Oring between it and the screw head and it took the metal on metal rattle out of it. 

[Likarok]

A can of silicone spray works miracles!