Read the Chevy High-Performance tech article on How to Program an OBD-II Powertrain Control Module.

"When GM builds the 6L80E at the factory, it installs a control module directly to the valve body. It houses all the pressure control solenoids, shift solenoids, and the transmission control ...

Dealers will install a new transmission control module software free of charge and GM will provide a special coverage program for repairing transmissions identified as containing a defective ...