Dodge 2012 Grand_Caravan - Owner Manual - Manual (Page 221)

The system will indicate a detected obstacle by showing
three solid arcs and will produce a one-half second tone.
As the vehicle moves closer to the object the EVIC
display will show fewer arcs and the sound tone will
change from slow, to fast, to continuous.
Slow Tone
Fast Tone
218 UNDERSTANDING THE FEATURES OF YOUR VEHICLE