Shift Solenoid 1
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
The shift solenoid 1 defaults to its normally closed state (OFF), allowing solenoid 1 signal fluid to exhaust from the shift solenoid valve - mode A, the hybrid direct, 2-3-4 clutch regulator valve, and the 1-3 clutch regulator valve.