1-3 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.
1-3 clutch regulator valve spring force moves the 1-3 clutch regulator valve to the released position, allowing 13 clutch/A cooling feed fluid pressure to exhaust through the valve into the backfill circuit.