[f5fstop]

Let me throw something out; and please remember, I am not there to hear the noise or see the conditions.
Does it only happen in a parking garage? Is the floor epoxy coated? I know the parking garage I was in a few weeks ago had epoxy coated floors; actually slippery when walking.
If you are sharply turning left, the right wheel might slip on the epoxy coated floor, and at that slow of a speed, if the traction control system becomes active, it will probably just apply the right front brake (engine management is one part of the TC system, but I don't believe it would be kicked in at such a low speed).
If it is the TC kicking in, it will apply the brake to the right front wheel; HOWEVER, the brake pressure modulator valve assembly is on the left side of the vehicle. When the modulator valve assembly operates it can give a ratcheting sound.
This sound might be heard better in an enclosed area such as a parking garage.
One way to test it is if you can always duplicate the sound in the parking garage, try it with the TC turned off. If the sound remains, it is not the TC system, if the sound goes away, it is the TC system.
If you have an automatic, just hold the TC button in for five seconds, and the DIC will display a message saying the stabilitrak is turn off, and so will be the TC system. If a manual, just press the button to turn off the TC.
I actually drove around the parking lot this morning in circles seeing if I could duplicate the sound, and I couldn't. But I was on rough concrete.
Just some weird ideas from the Pot Hole State.