OnStar Button Assembly Replacement (Pick-Up)
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 2001 GMC Yukon XL, 2001 GMC Yukon, 2001 GMC Sierra, 2001 GMC Cab & Chassis Sierra, and 2001 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
The OnStar button assembly located on the rearview mirror can not be serviced separately from the rearview mirror. Should the button assembly need to be replaced, the entire rearview mirror assembly will need to be replaced. Refer to Inside Rearview Mirror Replacement in Stationary Windows.