What's up with the high pitch noise when in 4WD?

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PokerMunkee

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I've rented a 2015 Suburban LT 4WD (12/14 build) and now renting a 2015 Tahoe LT 4WD (5/14 build). Both have the high pitch noise when the 4WD knob is in AUTO or 4HI. I've seen others complain of same issue.

It's VERY annoying!

Does GM have a fix? This is a deal breaker in my books, as I'm driving in adverse conditions a lot.
 

mwardncsu

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Curious about this as I have a 2015 Suburban LT - also with a 5/14 build date.

We recently purchased it used with about 25K miles on it - and have had my wife run it in 2WD due to the issues I've read of the transmission sometimes sticking in 4WD Low when run in auto mode. Today we had some snow so I switched it to 4WD High and would switch back to 2WD before parking - would hear a "thump" as it switched modes when stopped. I did not notice the high pitched noise others have mentioned - then again I've not run in the auto mode
 

SVL

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There are a few threads on here about it but to summarize: The control module that sits under the dash behind the selector knob generates this sound while the knob is in the "auto" position. Several have had the module replaced but the sound does not go away. The only fix I am aware of is wrapping the module in acoustic sound deadening material.

Pathetic to say the least.
 

Kazsmir

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My transfer case on my '15 Denali XL started whining under acceleration when in Auto/4Hi. Whine goes away when I shift it to 2WD. No whine under cruising or deceleration, but definitely there under acceleration and it didn't start until 29k miles.
 

15denali

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Mine does it too plus it feels like the 4wd is on all the time in auto/4h.
 

Shadow17

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More and more I am starting to appreciate the fact that I leased my Denali for 3 years and did not in fact purchase it.
Besides the obvious bookkeeping reasons, it sounds like I am going to be ready to move on after approximately 36K miles.
Question is- what to possibly move on to that carries 6 people, two dogs, and tows 9K #?
 

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