My problem is similar, but the bluetooth does turn on. (most of the time)
I have a Kenwood car radio that I hook-up to. I ran the initial pairing and connection, it worked just fine. But now, every time I start the car, I have to go into the SF's bluetooth settings menu, long press on the device name, choose "options", and check the "Phone - Use for phone audio" checkbox.
I wish there was a way I can get the phone and radio to connect automatically without going through this extra step each time.