WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Vacuum Control System Diagnostic, Testing Procedures (1 of 2)
Courtesy of GENERAL MOTORS CORP.
Fig 2: Vacuum Control System Diagnostic, Testing Procedures (2 of 2)