Drive Systems; All-Wheel Drive; Four-Wheel Drive - GMC 2012 Sierra Denali Owner's Manual

Grade Braking is only active while
the Tow/Haul Mode is selected and
you are not in the Range Selection
Mode. See Tow/Haul Mode listed
previously and Manual Mode on
page 9 37 for more information on
the Range Selection Mode. Grade
Braking assists in maintaining
desired vehicle speeds when driving
on downhill grades by automatically
implementing a shift schedule that
utilizes the engine and transmission
to slow the vehicle. This reduces
wear on the braking system and
increases control of the vehicle.
Grade Braking monitors vehicle
speed, acceleration, engine torque,
and brake pedal usage. Using this
information, it detects when the
truck is on a downhill grade and the
driver wants to slow the vehicle by
pressing the brake.
Also see Towing Equipment on
page 9 76 for more information.

Drive Systems

All-Wheel Drive

If the vehicle has this feature,
engine power is sent to all four
wheels when extra traction is
needed. This is like four-wheel
drive, but there is no separate lever
or switch to engage or disengage
the front axle. It is fully automatic,
and adjusts itself as needed for road
conditions.

Four-Wheel Drive

If the vehicle has Four-Wheel Drive,
you can send the engine's driving
power to all four wheels for extra
traction. To get the most satisfaction
out of Four-Wheel Drive, you must
be familiar with its operation.
Read the following before using
Four-Wheel Drive.
Driving and Operating
Notice: Driving on clean, dry
pavement in Four-Wheel Drive
High or Four-Wheel Drive Low for
an extended period of time may
cause premature wear on the
vehicle's powertrain. Do not drive
on clean, dry pavement in
Four-Wheel Drive High or
Four-Wheel Drive Low for
extended periods of time.
While driving on clean, dry
pavement and during tight turns,
you may experience vibration in the
steering system.
If the vehicle has StabiliTrak
shifting into Four-Wheel Drive Low
will turn Traction Control and
®
StabiliTrak off. See StabiliTrak
System on page 9 47.
Front Axle
The front axle engages and
disengages automatically when you
shift the transfer case. Some delay
for the axle to engage or disengage
is normal.
9-39
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