P0878 Condition 2
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 when engine shutdown is in process and the TFP switch 4 signal is HIGH for more than a period of time that is temperature dependent; 5 seconds for transmission fluid temperatures above 35°C (95°F) to 30 seconds at -20°C (-4°F).