Bluetooth connects, but does not play sound
I have the same problem.  I have a GTA Pure Bluetooth system in my 2007 Honda Civic. I have an iPhone 5S that connects automatically to play music about 5-10% of the time. To work around, I have to go into iPhone Settings, Bluetooth, select the ! symbol next to GTA Car Kit, Disconnect, back up one level and reselect GTA Car kit and it then connects 100% of the time. Kind of a pain.

It is almost like there are two levels of Bluetooth connectivity.  My phone connects perfectly 100% of the time but my music does not connect much at all.  In iPhones, look for the tiny headphone icon in the top-right corner of the screen when you have successfully connected to play music.