WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Power Brake Booster Vacuum Sensor
Courtesy of GENERAL MOTORS CORP.
Install the power brake booster vacuum sensor (1).
Connect the power brake booster vacuum sensor electrical connector.