I have Nav. So it powers up right when you open the door?

 

The drive does. That way it's booted and ready go quicker than if it waited 'til you actually selected the Nav function.

 

I don't have nav and mine does the same thing, sounds like a small fan motor that runs until the key is in the off pos. or the drivers side door is opened.

 

That's actually already been suggested several times in this post and I do not have the NAV.

 

That sounds more like the cooling fan for the radio unit....

 

I didn't even know there was a cooling fan for the radio. Learn something new every day.

 

I didn't know that existed either. However, I've pinpointed the noise, and it's coming from directly below the instrument panel cluster, not further to the right where the radio is located. Unless it's offset, I don't know that we're on the right track. Anyone else know if that part exists and if so, where it's located?

 

I have to admit I assumed it was the radio as that is when I would hear it come on, is with engine off, key in accessory and radio on.
HOWEVER I bet with the description Roccodawg just gave it could be a cooling fan for the BCM....

 

"Below the IP" listing...

2007 Chevrolet Tahoe - 2WD | Avalanche, Escalade, Suburban, Tahoe, Yukon (VIN C/K) Service Manual |

Below the I/P
(1) I/P Trim
(2) I/P Cluster Trim
(3) Floor Panel
(4) Junction Block - Left I/P
(5) Body Control Module (BCM)
(6) Transfer Case Shift Control Module (NP8)
(7) Fuse Block - I/P

 

Dang, w/ all of these cooling fans, it's no wonder the battery runs down so quick.