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: Identifying Headlamps Inoperative in Low Light Conditions Diagnostic Table (1 Of 2)
Courtesy of GENERAL MOTORS CORP.
Fig 2: Identifying Headlamps Inoperative in Low Light Conditions Diagnostic Table (2 Of 2)