Just found this Post from AC Delco tech tips. It is from September 2013.
Body Control Module Grounds - August 2013
2006-2011 Buick Lucerne, Cadillac DTS, 2008-2014 Buick Enclave, Cadillac CTS, Chevrolet Express, Chevrolet Traverse, GMC Savana, 2007-2009 Cadillac SRX, Chevrolet Equinox, Pontiac Torrent, 2007-2014 Cadillac Escalade models, Chevrolet Suburban, Chevrolet Tahoe, GMC Acadia, GMC Yukon models, 2006-2008 Chevrolet Monte Carlo, 2006-2013 Chevrolet Impala, 2007-2013 Chevrolet Avalanche, Chevrolet Silverado, GMC Sierra, 2007-2010 Saturn Outlook, 2008-2010 Saturn VUE, HUMMER H2
The Body Control Module (BCM) may be damaged when the module is supplied with battery power and the ground path is removed. Remove the negative battery cable first before removing a BCM ground.
BCM Ground Path
The BCM ground path passes through the following components. The negative battery cable must be removed on these vehicles when removing the components.
Instrument panel electrical center, 2008-2010 HUMMER H2
I/P splice pack, 2008-2010 Saturn VUE
Other Affected Components
When removing a ring terminal ground, splice pack connector, or inline harness connector on all the models listed, remove the negative battery cable if it is determined that it is a BCM ground path.
For example: If the BCM grounds become disconnected, internal damage to the BCM will occur. Other systems controlled by the BCM will also be affected, such as an inoperative or intermittent condition in one or more of the following systems:
Interior lighting will remain on or will not work
Exterior lighting will remain on or will not work
Remote keyless entry
Power windows and mirrors
Remote vehicle start
Remote trunk release