Conditions for Setting the DTC: P2670
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The TCM detects a short to ground on 2 or more of the solenoids (SS1, SS2, SS3, or PCS2) connected to the HSD2.