[colsanders]

I have a 04 CD navigation system. When navigating it does tell you directions while driving. Do you have the sound turned up on the voice navigation? Try setting a route, press the speaker icon as if your testing the voice and turn the volume knob to the right as if your increasing the volume.

 

[colsanders]

Click in the left knob where the volume control is. That shuts it off. I believe there also is an option by clicking the Band button for radio off.