stol1249

Less than 50 miles on the car and on my first drive since taking ownership of my 2012GS, I encountered a sudden high frequency whine, similar to a dentist's drill.

It is directly associated to the tach (RPMs)...the higher the rpms, the higher the pitch (frequency).

Does the C6 tach have an "electronic" association or is it a "mechanical" cable/gear drive to the tach? I suspect it is the tach connection that is causing the noise.

The dealer advsd to put some more miles on it and if it doesn't clear; to bring it in for service.

Appreciate advice, or has anyone else encountered this.

Turbo6TA

You woudn't happen to have the radio playing when you hear this noise do you?

GmdVT

bad bearing in your alternator, I just had mine replaced in my 09.

stol1249

No radio. Good thought though......I know that there can be electrical interference with radio.......but; no radio or CD.

Thanks.

Pete

stol1249

Great thought. The dealer mtce guy also thought it might be the alteenator breaking itself in; hence the "put some miles on it" response.

Thanks; I'll let him know your reply.

Pete

Zogs2011

I had to have the belt replaced on my 2011 with less than 300 mile, i am sure you know the difference in the 2 sounds but just something to check.

stol1249

Will advs the service advisor at Chevy; thnks.

Pete

Bill Dearborn

Sounds like an alternator bearing or maybe the belt tensioner. Tach gets its signal from the ECM. Mechanical tach drives which were a major headache to keep working were dropped over 30 years ago.

Bill

stol1249

I took a srewdriver end and listened to the alternator bearing; running smooth as glass. No noises coming from the pulleys/belt. The noise is coming from behind the dash (tach).

Very fine dentist drill whine.....increases and decreases in frequency with the RPMs.

waltershu

I had an 05, it was the clutch. If not a auto press the clutch when u hear it again.

stol1249

Pressing the clutch only lowers the frequency of the whine. In neutral or with depressed clutch the whine is still audible.

Thanks for the suggestion,

Pete

stol1249

OK folks, here's what caused the dentist drill type noise in my 12' GS.

Turned out to be a failed audio amp. Replacement of the amp also solved the intmt left speaker problem (both were related).

According to the tech advisor at Chevy, this is not the first of this type of failure.

Thanks for all your suggestions.

Pete

Indiana Z06

Great to hear you got it fixed!

Gearhead Jim

And thanks for posting the results!