Action Taken When the DTC Sets

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.

The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
DTC P0634 is stored in TCM history.
The TCM shuts down and all power is removed from the solenoids.
The transmission goes to a hydraulic default mode and will operate in reverse, neutral, and first, third, or fifth range.