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grizzlyrafting

High frequency noise coming from dash when in 4WD

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Ok, there may be some forward progress here!! My hometown dealer has had a few customers bring in their trucks complaining of this issue. Apparently this dealer has staff with better hearing than most. Anyways, it merited a visit from gm engineering and they have said it is electrical feedback from the rear differential having too much backlash (slack between gear teeth apparently). Each dealer is equipped with a dial indicator and can test the backlash. The engineer advised a rear differential replacement. Too early to tell whether this will ultimately fix the issue, but we shall find out soon once it is replaced. I will post any results as I have them

 

 

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Keep us posted. I tried every truck on the lot, they ALL do it. Not holding my breath this is the fix, but at same time crossing my fingers.

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Just got back from the dealer with the same issue. They insist i'm the first to complain but that there is a GM service bulletin saying that the noise is normal and associated with the transfer case. What a load of crap. I understand that 4wd can be louder but this is clearly an electronic, high frequency noise that should not be there. In my estimation this is clearly an engineering/fabrication issue and should definitely not be considered 'correct', even if 'normal'.

Edited by Kcitti

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My dealership received a possible band-aid from GM - a piece of insulation to try and deaden the sound. They installed it on another 2015 truck on their lot and let me listen. Unfortunately, it didn't deaden the sound. It was still clearly audible.

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Called dealer today, rear differential will be done by Monday. They are already ordering more rear differentials based or corporate engineering claiming this will fix issue. Supposedly slippage is causing electrical feedback as the system attempts to engage and adjust. Will advise on Monday.

 

 

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I kinda like it....reminds me that I am in 4wd. Seems like it goes away after it warms up, Inhabent been out of 4wd this entire week here in KY.

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Yes please do. I just purchased a Silverado and heard the noise in Auto only (might have heard it quick in 4HI while turning) I still bought it since I won't really use Auto too often but I would like it fixed. If it's backlash from the rear diff then it should be fixed.

Yes please do. I just purchased a Silverado and heard the noise in Auto only (might have heard it quick in 4HI while turning) I still bought it since I won't really use Auto too often but I would like it fixed. If it's backlash from the rear diff then it should be fixed.

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beezermascu Can we get your dealer info since mine will likely deny the issue? Warranty covered I assume?

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Called dealer today, rear differential will be done by Monday. They are already ordering more rear differentials based or corporate engineering claiming this will fix issue. Supposedly slippage is causing electrical feedback as the system attempts to engage and adjust. Will advise on Monday.

 

 

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Any update??

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#PIP5261: Faint High Pitched Whine Noise In Auto 4 Wheel Drive - (Jan 29, 2015)
Subject: Faint High Pitched Whine Noise In Auto 4 Wheel Drive 999999995.gif Models: 2014-2015 Chevrolet Silverado 2014-2015 GMC Sierra 2015 Chevrolet Suburban Tahoe 2015 GMC Yukon, Yukon XL, Yukon Denali 2015 Cadillac Escalade, Escalade ESV Equipped with 4 wd RPO NQH or NP0

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern

Some customers may comment on a high pitched whine noise from the vehicle noticed when driving in auto 4wd. The customer may comment that it is an intermittent noise and no noticeable pattern to when it can be heard.

Recommendation/Instructions

The transfer case control module on these vehicles is located next to the accelerator pedal and is not covered by any close out or hush panels.

When the transfer case control module has to move the transfer case actuator motor the higher current passing through the module causes an "electronic buzz or whine" within some of the capacitors in the module that can be heard by some of our customers.

Typically this can only be heard with all accessories and HVAC off and only when actuator movement is required. This does not indicate a concern with the module and should not be replaced to address this concern.

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So the question remains, if "This does not indicate a concern with the module and should not be replaced to address this concern.", then how should the issue be addressed?

 

I'm afraid "it shouldn't be" will end up being the answer.

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