Power Ground
WARNING: This page does not describe the selected car, but rather 30 other vehicles, including the 2004 Mercury Sable, 2004 Mercury Mountaineer, 2004 Mercury Monterey, 2004 Mercury Marauder, and 2004 Mercury Grand Marquis. However, it is still accessible from the selected car via links, so may be relevant.
Power ground (PWR GND) is an electric current path return for VPWR voltage circuit. The purpose of the PWR GND is to maintain sufficient voltage at the PCM.