Jeep 2015 Grand Cherokee - Owner Manual - Manual (Page 224)

If an obstacle is detected in the left and/or right rear
region, the display will show a single arc in the left
and/or right rear region and the system will produce a
tone. As the vehicle moves closer to the obstacle, the
display will show the single arc moving closer to the
vehicle and the tone will change from a single 1/2 second
tone to slow, to fast, to continuous.
Single 1/2 Second Tone
222 UNDERSTANDING THE FEATURES OF YOUR VEHICLE