I called Lowrance and went thru several steps with the Level 1 tech, to no avail. Fortunately, he forwarded me to His Supervisor Bonnie, who had me verify the Lowrance Software version. I had Version 2.0, she said there was bugs in that software that prevented proper syncing. She had me download the most recent Lowrance software, version 4.0, to a micro SD card and install 4.0 to the HDS. She then had me clear my phone and the HDS Carbon of the previous download attempts. Previously my iPhone was showing HDS-12c as a Bluetooth source, and the HDS was showing my IPhone, however it never worked. I then started fresh, pairing the phone to the HDS and it worked. The Bluetooth source shows up on your phone and the HDS-12 Carbon as Sonichub2. This is KEY: Both the HDS Carbon and IPhone show the same source: Sonichub2. I now can play both Pandora and my iTunes from my phone to the boat speakers. I hope this helps others with similar issues.
Edited by Dr. Hook (04/16/18 12:09 PM)