RAM 2500 2019 Owner's Manual page 393

STARTING AND OPERATING 391
5
Fast Tone Continuous Tone
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.