What I am trying to do is use my phone as GPS and have the voice prompts to be played through the car speakers. However, if I set my audio source to bluetooth the car would also play songs on my phone concurrently.

Is there anyway to only output the GPS voice while still listen to music from another source?

 

No, once the headunit is set to a certain function it will only have audio input from that function, you cannot combine bluetooth and iPod for example.

 

That is not technically true... If you have HFP Prompts you can certainly do the above. this is fully available in on iPhones and i believe all the galaxy models. This will act like a "phone call" and send the map prompt through your speakers.

Hope this helps.