Dodge Dart 2013 Owner's Manual page 236

234 UNDERSTANDING THE FEATURES OF YOUR VEHICLE
If an object is detected in the center rear region, the
display will show a single solid arc in the center rear
region and will produce a one-half second tone. As the
vehicle moves closer to the object, the display will show
the single arc moving closer to the vehicle and the sound
tone will change from slow, to fast, to continuous.
If an object is detected in the left and/or right rear region,
the display will show a single flashing arc in the left
and/or right rear region and will produce a fast sound
tone. As the vehicle moves closer to the object, the
display will show the single arc moving closer to the
vehicle and the sound tone will change from fast, to
One-Half Second Tone
continuous.