Hybrid Low, 1-2 Clutch Regulator Valve
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.
Hybrid low, 1-2 clutch regulator valve spring force moves the hybrid low, 1-2 clutch regulator valve to the released position, allowing excess backfill pressure to exhaust through the valve into the HL 12 clutch/4th clutch feed circuit.