WARNING: This page is about a different car, the 2013 Acura MDX, 2012 Acura MDX, 2011 Acura MDX, and 2010 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
This checks the GA-NET Bus line to the XM receiver.
When connection is shown with NG, check the connection between the XM receiver and the audio-navigation unit.