Conditions for Setting the DTC: P0961
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.
The transmission control module detects an internal electrical performance malfunction of the line pressure control solenoid control circuit and the actual line pressure does not equal the commanded line pressure for 300 milliseconds.