One problem related to battery dead has been reported for the 2009 Ford Flex. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2009 Ford Flex based on all problems reported for the 2009 Flex.
Passenger door ajar dash light goes on and off when the door is secure and locked. Interior lights go on and off when ajar light is displayed and power locks unlock/lock at the same time. This is a serious issue at night when the interior lights go on and off the entire time when your driving blinding you as well as I have been pulled over because they thought I stole the car. While pulled over I was asked to step out of the car and when I exited the car ibecame possessed and the alarm went off and interior lights began blinking and flashing on and off. The car alarm consistently goes off at all hours of the day and night causing the battery to go dead if your not around to shut it off. This is also issue as my car can get stolen at any time if the factory alarm isn't working or I could get carjacked because the doors won't stay locked. This issue happens in park, in drive and reverse. It happens while driving or idling as well as it occurs on the highway and city streets. I have read many other reports and Ford needs to address this in the 2009 Flex as well.