Vibration

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Feb 16, 2023 | 09:29 AM

Jack Rice

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Heel & Toe

Joined: Aug 2009

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Vibration

I have a vibration when traveling with cruse control on. Turn off control vibration goes away.
I was told by 2 owners of C7 that transmission is cause, and having fluid flushed and new
put in will clear the problem. Does any one know of this?

jackrce1944@gmail.com

Feb 16, 2023 | 09:30 AM

squirrelchew

Burning Brakes

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From: MSP

sounds like you have an 8AT? put it in manual mode, see if the vibration goes away. if so, the cause is the v4 mode for fuel economy.. but that isn't unique to cruise control.

tons and tons and tons of threads on this. at least one of them is stickied!

Feb 16, 2023 | 12:09 PM

SIELMO

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Joined: Apr 2019

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From: Ewa Beach, HI.

Similar issue albeit not with cruise control but just light throttle....brought it up to our local Chevy dealer last week and provided the TSB number. They investigated and did the triple flush as described. I've had the car back for a few days and I notice a difference. V8 to V4 transition unnoticeable now, no more "washboard" like experience, and my gas mileage ticked up a tad. Bottom line, a noticeable improvement. Chevy covered the cost, ($810)

Feb 16, 2023 | 12:26 PM

Vetteman Jack

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^ I agree with looking into the triple flush on the transmission, assuming you have an A8.

Feb 16, 2023 | 01:07 PM

SIELMO

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Joined: Apr 2019

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From: Ewa Beach, HI.

Quote:

Originally Posted by Vetteman Jack

^ I agree with looking into the triple flush on the transmission, assuming you have an A8.

Yes, 2018 GS w/A8.

Feb 17, 2023 | 02:38 PM

ShadyVette

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From: Boston

For about 900 get a tranny filter replaced. Gives new fluid and gets filings out. Add in a range finder to keep away from V4 and you’ll have plenty of trouble free years.

Feb 17, 2023 | 02:56 PM

Gearhead Jim

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Quote:

Originally Posted by ShadyVette

For about 900 get a tranny filter replaced. Gives new fluid and gets filings out. Add in a range finder to keep away from V4 and you’ll have plenty of trouble free years.

Getting the filter replaced is nice, but doesn't get all the old fluid out; that's the purpose of the triple flush. If GM thought that 1 fluid exchange and a new filter would cure the problem, they'd be recommending that instead of the triple flush detailed in the GM bulletin.

Of course, OP's problem could be something else and then it gets complicated.