Compass Calibration and Variance Procedures
WARNING: This page is about a different car, the 2011 GMC Sierra, 2011 GMC Cab & Chassis Sierra, 2011 Chevrolet Silverado, and 2011 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
When the inside rearview mirror with compass is replaced, the compass must be setup utilizing the Compass Calibration and Magnetic Variance (without OnStar Only) .