1-2 Shift Valve
WARNING: This page is about a different car, the 2009 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
Fluid pressure from the 1-2 SS valve holds the 1-2 shift valve in the downshifted position. The valve allows orificed Low feed to pass through the valve and enter the Low & Reverse band reduce circuit. Low & Reverse band reduce is then routed to checkball #6 and to the spring side of the Low & Reverse servo piston.