High Pitched Whining Sound at High Speeds

[Sdnyc82]

Hi folks

I have a 19 Limited with 43k on the dash . When I go 70+mph on the highway, I hear a distinct high pitched or whistling sound from underneath the truck that comes and goes. When it comes, it is very noticeable. It is almost like a beeping sound, but not always beeping at the same rate. It doesn't change when I'm accelerating, but the beeps get closer together as I'm going faster. Sometimes it doesn't happen at all, even at 80mph.

A little research told me it might be something in the differential?

 

[Fatherof3]

I’m not 100% sure but if it was the differential it would do it all the time ?

 

[Sdnyc82]

I’m not 100% sure but if it was the differential it would do it all the time ?

It doesn't do it all the time. Today I went all day without hearing it, but the other day I heard it a couple of times- driving under the same conditions, obviously.

 

[c3k]

Temperature changes when you hear/don't hear it?

I'd crawl underneath and look at all the drivetrain components, from the wheels up to the transmission output. Look for any indications of wear. Could be something rubbing, but only "just" touching: when it's hot, the clearance is reduced and you hear it?

A slight wear mark may be the clue. (Rocks behind heat shields are a favorite.)

 

[Scram1500]

Could be the active noise cancellation system malfunctioning as well