1-2 Shift Solenoid Valve
WARNING: This page is about a different car, the 2004 Pontiac Sunfire, 2004 Chevrolet Classic, and 2004 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The PCM keeps the solenoid valve energized in Reverse position. The 1-2 signal fluid pressure acts on the 1-2 shift valve.