RAM 1500 Owner's Manual page 406

404 STARTING AND OPERATING
You can switch between DRIVE and ERS mode at any
vehicle speed. When the shifter switch is in the DRIVE
position, the transmission will operate automatically,
shifting between all available gears. Tapping the ERS (-)
switch (on the steering wheel) will activate ERS mode,
display the current gear in the instrument cluster, and
maintain that gear as the top available gear. Once in ERS
mode, tapping the ERS (-) or (+) switch will change the
top available gear.
1 — ERS (-) Switch 2 — ERS (+) Switch