Low & Reverse Clutch
WARNING: This page is about a different car, the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Cadillac Escalade EXT, 2007 Cadillac Escalade ESV, and 2007 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
CBR & CBR1 fluid pressures are routed to both the inner and outer areas of the low and reverse clutch piston to hold the piston against spring force and hold the low and reverse clutch plates. The clutch was already applied in Park, but is applied with more holding capacity in Reverse (both piston areas are pressurized).