Gabe,
Do you have the same noise coming out on your Yukon?
Yes I did take it to service, and after many tests, they manageed to duplicate the sound using Tech 2, and the sound turned out to be coming out of the ABS motor pump.which they said it is normal in some specific circumstances. they send teh data to the Tac team, if there is a fix they will let me know.

hope this helps
Guss

 

Guys: the dealer Tech 2 tool has the capability to override battery cooling fan control and turn it up just sitting there. The fan is close to the drivers side rear door on the floor under middle row seat. If it is the battery fan it will come from there

The Tech 2 can turn on the Auxillary transmission pump at several speeds. Aux pump buzzing or oil cooler lines that are transferring the buzz to the frame will be loudest on the drivers side under the front wheel well. If you put your head near the left front wheel, that is where Aux pumps sound will be loudest. They may even be able to force the electric brake pump on. The brake pump is under floor under the drivers seat area.

All these can be done one-at-a-time to isolate the source.

You all can slowly pump the brake pedal and force the brake pump on just sitting in Auto-Stop with the drivers door open to hear better. If the door chime is too loud with door open, I pull around back of a quiet brick building or near tall concrete curb. With the vehicle about 6 feet or 2 meters from the hard sound reflecting surface you can try things to force the noise. McDonalds drive throughs are perfect for reflecting any under body noise right to your ear.

Once you can repeat the noise, any tech worth his salt should be albe to find it. (without part swap roulette)

 

Thanks Hillibilly

 

Thanks for the info Guss. I do have that same noise...

I have mine into the dealer and they can not duplicate the sound as of yet, of course it seems to happen to me couple times a week (go figure). I at least want to get this problem documented with the dealer, especially if it is something to do with the ABS motor, makes me nervous now if that is the problem, as I hull kids around. Even though your dealer said it's in some cases normal. I'm not sure how that noise would be "considered" normal. I forwarded some of your info on to my dealer in hopes they at least will get my issue in the system and research it more.

It's been frustrating to say the least and also very disruptive hearing that noise. I would appreciate you keeping me updated on your progress with your dealer on seeing if they will have a fix.

Thanks again Guss.

 

Gabie,
They duplicated the sound in front of me using the Tech 2, by going into the EBCM: Electronic Brake Control module Menu, then turning the ABS pump motor ON Manually. The sound came out identical to the original sound but on a much lower level. (They explained to me that the sound level depends on the air and pressure that is stored in the braking system based on the brake usage). The more I use the brakes paddle the more air and pressure is built up in the system and in certain circumstances and when the vehicle goes into auto stop, the sound is heard much louder where the pump motor is working to release the air out of the system. They even managed to duplicate the sound on a much lower level while the engine was running once the ABS pump motor was turned on manually.
It happens more often in hot weather than cold. so usually in the summer.
They did the same test to a brand new 2010 tahoe identical to mine, and they same sound came out as well.
They say it is normal, so I hope the TAC team send them a softwrae update or a fix soon.
As long as I have it on record, it shoudl be covered by the warranty even after expiration.
Hope this helps, will let you know if anythign comes up. but there is no risk on the brakes at all as far as I know.

 

Buzz update or "hold my beer watch this". Hillbilly theory to test.

The buzzing may be related to some valve and spring combination in the valve body being set off by as yet an undetermined reason. For the engineers that still remember the square root of (k/m) where k is the spring factor and m is mass. That is omega or the buzz frequency.

What is missing in this noisy dashpot is damping!

Try and add about 1.5 quarts or liters of transmission fluid. It just might raise the liquid level enough to dampen this noise out.

If the theroy is correct. I'll be a buzz kill.

 

Heard this same loud noise while being questioned by border police on the Canadian border today. I had been driving on the hwy for a couple of hours and waited in line for a short bit.

First time hearing it. Duration 10 seconds if that? Border lady was like is this a new noise? I said it is a hybrid model so it makes weird noises some times.

Sounds like this is pretty de rigueur? I have 1k miles on my 2013 now.

 

CYKBC,
Were in Canada are you? I am currently living in Toronto area, just moved here last may, sold my Tahoe back home.
I can hardly find GM Hybrids in Canada, even the dealers don't carry them!!!
If you come my way please let me know, would love to check out the new 2013 Hybrid

Regards,

Guss

 

hey guss, appreciate you documenting this while you still had it!

i'm over in vancouver. if you're ever out west, would be more than happy to give you the keys for ol times sake!

 

Thanks for your Offer, will keep it in mind
I guess they never managed fixed that issue yet.