Question about Bluetooth and Cortana

[littlejay]

On my n920 running 8.1, when I used bluetooth in my car, Cortana would run without turning on the phone in my pocket. Now that I have upgraded to a 1520 with 8.1, the phone turns on everytime I use bluetooth to activate Cortana. Is there a setting I don't know about to fix this? I don't want the phone on and unlocked in my pocket.