Conditions for Setting the DTC: P0776
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
This DTC sets during a shift when the calculated commanded gear ratio differs from the known commanded gear ratio for more than 2 seconds.