Dodge 2004 Ram 2500 Owner's Manual page 220

220 STARTING AND OPERATING
"1" First
Use this position for driving up very steep hills and for
engine braking at low speeds 20 mph (32 km/h) or less
when going downhill. To prevent excessive engine speed,
do not exceed 25 mph (40 km/h) in this range.
NOTE: Use caution when operating a heavily loaded
vehicle in "2" Second or "1" First gear selections in high
ambients as torque converter slip can impose significant
additional heat load on the cooling system.
WARNING!
Never use Park position on an automatic transmis-
sion as a substitute for the parking brake. Always
apply parking brake fully when parked to guard
against vehicle movement and possible injury or
damage.
Overdrive Operation
The four-speed overdrive automatic transmission con-
tains an electronically controlled fourth speed (Over-
drive). The transmission will automatically shift from
Drive to Overdrive if the following conditions are
present:
• the transmission selector is in Drive;