Shift Solenoid Valve - Mode B
WARNING: This page is about a different car, the 2010 GMC Sierra and 2010 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
HL 12 clutch/4th clutch feed fluid is routed to the shift solenoid valve - mode B, where it passes through the valve into the HL 12 clutch circuit.