Interior tones are sounding in the cabin intermittently.
Everyone is used to the tone you get when you don't buckle your seatbelt but
besides that my Grand Marquis started delivering a tone regularly every 20
minutes while the car is operating. It sounds a dozen times or so then repeats
in another 20 minutes. I can't find anything that indicates what it might be
signaling or how to turn it off. Does anyone have any ideas.