The multi-band antenna is on the roof of the vehicle. The antenna is used for AM-FM radio, OnStar, the SiriusXM satellite radio service system, and GPS (Global Positioning System), if the vehicle has these features. Keep the antenna clear of obstructions for clear reception.
If the vehicle has a sunroof, and it is open, reception can also be affected.
Radio Reception
Audio Players#13-00-89-004C: Car and Truck Fix it Right the First Time Issues - (Oct 10, 2013)
Subject:Car and Truck Fix it Right the First Time IssuesModels: 2014 and Prior GM Cars and Trucks This bulletin has been revised to include updated information. Please discard CorporateBulletin Number 13-00-89-004B.In order to access this bulletin electronically, go to the SI Home Page and selec ...