Diagnostic Aids
WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
When attempting to set transmission control module internal DTCs, run the engine for at least 1 minute, and then shut the engine off for 30 seconds. Following this procedure will allow for a complete transmission control module shutdown.