Loud Whining noise while pressing brake paddle in park-drive.
 

I have been experiencing a loud whining noise with my Tahoe when I have my foot on the brake paddle for few minutes (2+ mins) before shifting out of park to Drive.
Once I shift to drive, a loud whining and squeaking comes out from the engine compartment area. You hear it from the outside, when the door or window is open. People can notice it.
Once I remove my foot from the brakes, it stops, if I put it back it comes out again, unless I put it back to park and remove my foot off the paddle.

I only noticed it happen twice so far.
It seems as if something heats up when I rest my foot on the brake paddle for a long time while in park? Is that possible?

Anyone experienced this noise before?

any feedback is highly appreciated

Re: Loud Whining noise while pressing brake paddle in park-drive.
 

ive never found the need to sit with my car in park or drive and my foot on the brake for an extended period.
i always shift to park. no need for the brakes when its in park

Re: Loud Whining noise while pressing brake paddle in park-drive.
 

Might be coming from the electric brake boost pump. But I agree with Jet. Why would you sit in park with the foot on the brake that long? If I park on a grade, I engage the park brake.

Re: Loud Whining noise while pressing brake paddle in park-drive.
 

Thanks guys,
yes the electric brake boost pump makes sense.will this appear in the diagnostic computer test if I take it to the dealer? is there any risk dirving it ?will it fail suddenly?
I usually don't sit with foot on paddle, but sometimes when I am about to move, and wife decides to fix baby seat or something, I end up waiting impatiently with foot on brake paddle :)

Re: Loud Whining noise while pressing brake paddle in park-drive.
 

I have had something like this happen when I am waiting at a drive thru window. It can startle you because it is otherwise so quiet. Now I wasn't shifting but maybe the common element is having your foot on the brakes for awhile.

Re: Loud Whining noise while pressing brake paddle in park-drive.
 

Guss, it is always possible it could fail suddenly, but you would only loose boost, not brakes. You will still have braking power. I doubt the computer will catch the noise, but the dealer may be able to run a diagnostic to detect a pump that is starting to fail. See if you can reproduce it again, that would be the best way to get the dealer to experience the issue.

Re: Loud Whining noise while pressing brake paddle in park-drive.
 

Brake boost system has a little accumulator that has to be charged. I'm guessing if you have the pedal depressed the accumulator is draining, then the boost pump has to cycle again to pump it back up.

This is normal. Your brake system sounds fine.

Bottom line: Put it in park if you're going to be sitting for a while, like any other car.

Re: Loud Whining noise while pressing brake paddle in park-drive.
 

Thanks Fj, and KC.

I wil try to reproduce the sound again and see if it happen more often, then I will take it to the dealer.
FYI The sound comes out when I am in Drive not while in Park.

will keep you posted for any updates

Re: Loud Whining noise while pressing brake paddle in park-drive.
 

I would here noises myself but loved it. it sounds like a plane taxiing the runway.