2025 high country rustling noise above 80moh

My 2025 Tahoe high country makes windy, ratting, rustling sound above 80 mph. It appears to be coming from right rear area of the car. It sounds like something rattling around in the wind, like plastic bag, paper, or maybe a wiring harness. It's been on a lift and there's nothing obvious. It's been to the dealer 3 times and they haven't done anything else to find the problem. It's clear that they don't want to mess with it and at this point I don't trust them to. Any thoughts?

SWAG Active grill shutter acting up?

What/where is that?

In the grill, in front of the radiator.

I would check the plastic side pieces above the rear light assemblies. If you can move them even the slightest with your hand, when I'd wedge a piece of zip tie into the crevice with the least opening width and go for a drive. At speeds above 80, there is some real aerodynamic suction going on at the rear of the truck.

agree it's probably a loose piece of trim/bumper/cover/siding, mud flap, etc maybe even under the vehicle.
check all the exterior pieces, push and pull on everything.
check the roof too
AND if you installed anything 3rd party like a bug or window wind protector those are infamous
even aftermarket window wipers

JBravo1977 said:

My 2025 Tahoe high country makes windy, ratting, rustling sound above 80 mph. It appears to be coming from right rear area of the car. It sounds like something rattling around in the wind, like plastic bag, paper, or maybe a wiring harness. It's been on a lift and there's nothing obvious. It's been to the dealer 3 times and they haven't done anything else to find the problem. It's clear that they don't want to mess with it and at this point I don't trust them to. Any thoughts?

Click to expand...

The dealership clearly doesn't want to mess with this problem. After they let it sit all day without anybody looking at it the THIRD TIME I had an appointment for them to look at this, they asked me to leave it with them for four days. I have little doubt that it would be left outside with the window rolled down or who-knows-what-else for 4 days while they try to put me in a loaner Traverse, so I really don't want to do that.

I've isolated the noise to the passenger side back door (2nd row door, not the rear hatch/liftgate) area. It's odd that it only does this at about 80 mph and above. If anybody has any thoughts I would really appreciate it. Thanks!

Doubeleive said:

agree it's probably a loose piece of trim/bumper/cover/siding, mud flap, etc maybe even under the vehicle.
check all the exterior pieces, push and pull on everything.
check the roof too
AND if you installed anything 3rd party like a bug or window wind protector those are infamous
even aftermarket window wipers

Click to expand...

I love the Duke Nukem 3D avatar. I was in college when that came out, in the early days of online PC gaming, and spent hours playing that and C&C.

I installed some aftermarket black covers over the chrome window trim because almost everything else on the truck is murdered out except a couple of pieces of window trim, which seems crazy to me. I did both sides, but only 1 side has this problem. I tried taping it down with some painters tape to make sure air couldn't get under it but that didn't help. I guess that could still be the problem though. Is there anything inside the door assembly that could be catching high speed air and rattling?

You don’t have crossbars installed do you?