Park - Engine Running: Notes
WARNING: This page is about a different car, the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
With the gear selector lever in the PARK (P) position and the engine running, the line pressure from the oil pump assembly is directed to various components in the valve body and the oil pump.