AIR Vacuum Control Solenoid
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
The AIR vacuum control solenoid controls the AIR Shut Off Valve. When the secondary air injection system is enabled, the control module provides a ground to the solenoid. Enabling the solenoid allows the engine vacuum to be applied to the AIR shut off valve.