Power Mirror System Controls
WARNING: This page is about a different car, the 2019 Buick Cascada, 2018 Buick Cascada, and 2017 Buick Cascada. However, it is still accessible from the selected car via links, so may be relevant.
The outside rearview mirror switch is a four position directional switch: Up, Down, Left and Right.
The mirror select switch is a three position switch: left, neutral/fold, and right.