RAM 1500 Owner's Manual page 509

STARTING AND OPERATING 507
You can switch between DRIVE and ERS mode at any
vehicle speed. When the gear selector is in the DRIVE
position, the transmission will operate automatically,
shifting between all available gears. Tapping the ERS (-)
switch (column shift) or tapping the gear selector to the
left (-) (console shift) will activate ERS mode, display the
current gear in the instrument cluster, and set that gear as
the top available gear. For example, if you are in DRIVE
5
and are in third (direct) gear, when you tap the gear
selector/switch one time in the (-) direction, the display
will show 4 (ERS 4 is direct gear). Another tap down (-)
will shift the transmission down to ERS 3 (the added
Column Gear Selector
underdrive gear). Once in ERS mode, tapping (-) or (+)
will change the top available gear.