2020 Silverado whistling noise

[Mario C]

2020 Silverado. Whistling noise from front end. Had wheel bearing checked all good. Happens at around 30 miles an hour. Not brakes. Also when truck has been travelling for awhile. For what ever reason I switched to 4x4 and noise stopped. Could it be something in differential. 

[gemarsh]

Does the truck have the "optional louvers package"? I believe they open in 4x4. Would be a quick check to see if the louvers are fully closing. 

 

Now I'm interested. I wonder if they open in Tow/Haul mode.

 

You could also see if the whistling stops in T/H mode.

 

I cannot imagine the front diff would produce a whistling sound.

[Mario C]

I will try in tow haul mode. Not sure what these louvers are. How can I tell if the truck has them. 

[gemarsh]

https://gmauthority.com/blog/gm/general-motors-technology/gm-aerodynamics-technology/gm-active-aero-shutters-technology/