Low & Reverse Servo
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.
Low & Reverse band reduce fluid from the 1-2 shift valve seats checkball #6 against the Low & Reverse band apply passage. Fluid is then routed to the spring side of the Low & Reverse servo piston, and into the reverse clutch circuit. In this gear range the Low & Reverse band remains applied, despite the spring force and the Low & Reverse band pressure acting on the Low & Reverse servo piston.