Chasing down a vibration noise

[Elkins45]

Next to an intermittent electrical fault there’s nothing more annoying than trying to find a rattle. My 09 Scion has started making a really annoying buzzing rattle from somewhere in the rear. I unloaded everything in the back including the jack, spare and other assorted gear but that wasn’t it. Arrgghhh! My first thought was maybe the back hatch glass is loose but I believe that it is glued in. It seems to be a harmonic because hitting bumps doesn’t cause it but it’s somehow influenced by holding the brakes at a stoplight. Exhaust bracket maybe?

I’m hoping something will be obvious when I crawl under it tomorrow. I was planning on putting it up for sale soon but who would buy it when it’s making noises?

 

[Pterostylis]

Similar sounding thing happened to a relatives car that I service, I tracked it down to something in the rear muffler. Probably a collapsed baffle as it’s over 20 years old but I guess some idiot could have put a marble in there.
I will fit the new muffler for them this weekend.

 

[CharBaby]

If you’re saying that the vibration is in the rear, I’ve often had to fix the muffler heat shield on vehicles. A rivet(s) that are mounted to that shield, above the muffler(attached to the underside of the trunk) had broken/rotted, causing the vibration. Hmmm IDK, give it a look see!