Yesterday I was driving, and the "Check Charging System " message popped up on my message center and also a light came on. It went away seconds later, but then came back two more times but they went away after a few seconds. This used to pop up often, and when my car was getting another problem fixed at the Ford Dealership they replaced my alternator (few months ago). Today when I was driving a heard the beep (the beep that goess off when there is a message or low fuel level), but no lights came lit up on the dashboard and no message came up. I heard this beep a few times... Any ideas what the beep is or why it said Check charging system?