One problem related to differential unit has been reported for the 2009 Jeep Patriot. The most recently reported issues are listed below.
Spouse has just made a turn and was driving home in the country when she heard a loud pop followed by a loud noise from the rear of the car with vehicle vibration. She pulled over to the side of the road and noticed the rear wheel driver side was on an angle. Husband showed up to see what happened and it appears the rear subframe cracked under severe corrosion allowing the left rear axle to pop out of the differential. Vehicle was then towed home.