OnStar Button Assembly Replacement (Pick-Up)
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2004 GMC Yukon XL, 2004 GMC Yukon, 2004 Chevrolet Tahoe, 2004 Chevrolet Suburban, and 2004 Chevrolet Avalanche. 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 Rearview Mirror Replacement in Stationary Windows.