I'm having trouble hardwiring my X50 in my Jeep Liberty. I've chosen to run it off the stereo's 12v power. So I spliced into the yellow wire (MAIN POWER) and the black wire (GROUND). The thing powers up with the car off for some reason. I do NOT want this to happen. My cig lighter is 6v and is always on so that's not an option. Can anyone suggest a solution here as to why I'm getting power with the key not in?