GMC Yukon Denalid Owner's Manual page 148

DRIVE (D): This position is for normal driving. It
provides the best fuel economy for your vehicle.
If you need more power for passing, and you are:
•
Going less than about 35 mph (55 km/h), push
your accelerator pedal about halfway down.
•
Going about 35 mph (55 km/h) or more, push
the accelerator all the way down.
Drive (D) can be used when towing a trailer,
carrying a heavy load, driving on steep hills,
or for off-road driving. You may want to shift the
transmission to a lower gear selection if the
transmission shifts too often.
Downshifting the transmission in slippery road
conditions could result in skidding, see Skidding
under Loss of Control on page 357.
When temperatures are very cold, the
®
Hydra-Matic Automatic Transmission's gear
shifting may be delayed providing more stable
shifts until the engine warms up. Shifts may
be more noticeable with a cold transmission.
This difference in shifting is normal.
148
MANUAL MODE (M): This position lets drivers
select the range of gears appropriate for current
driving conditions. If your vehicle has this feature,
see "Driver Shift Control" later in this section.
Notice: Spinning the tires or holding the
vehicle in one place on a hill using only
the accelerator pedal may damage the
transmission. If you are stuck, do not spin
the tires. When stopping on a hill, use
the brakes to hold the vehicle in place.
Your vehicle has a shift stabilization feature that
adjusts the transmission shifting to the current
driving conditions in order to reduce rapid upshifts
and downshifts. This shift stabilization feature is
designed to determine, before making an upshift,
if the engine will be able to maintain vehicle
speed by analyzing things such as throttle position,
vehicle load, and hill grade. If the shift stabilization
feature determines that a current vehicle speed
cannot be maintained, the transmission does
not upshift and instead holds the current gear.
In some cases, this may appear to be a delayed
shift, however the transmission is operating
normally.