Service Four Wheel Drive - GMC 2012 Yukon/Yukon XL Owner's Manual

AUTO (Automatic Four-Wheel
Drive): This setting is ideal for use
when road surface traction
conditions are variable. When
driving the vehicle in AUTO, the
front axle is engaged, and the
vehicle's power is sent to the front
and rear wheels automatically
based on driving conditions. Driving
in this mode results in slightly lower
fuel economy than Two-Wheel
Drive High.
4 (Four-Wheel Drive High): Use
the Four-Wheel Drive High position
when you need extra traction, such
as on snowy or icy roads or in most
off-road situations. This setting also
engages the front axle to help drive
the vehicle. This is the best setting
to use when plowing snow.

Service Four Wheel Drive

If the SERVICE 4 WHEEL DRIVE
message stays on, you should take
the vehicle to your dealer for
service. See SERVICE 4 WHEEL
DRIVE message under
.
Shifting Into Four-Wheel Drive
High or AUTO (Automatic
Four-Wheel Drive)
Turn the knob to the Four-Wheel
Drive High or AUTO position. This
can be done at any speed. The
indicator light will flash while
shifting. It will remain on when the
shift is completed.
Driving and Operating
Shifting Into Two-Wheel
Drive High
Turn the knob to the Two-Wheel
Drive High position. This can be
done at any speed. The indicator
light will flash while shifting. It will
remain on when the shift is
completed.
Excessively shifting the transfer
case into or out of the different
modes may cause the transfer case
to enter the shift protection mode.
This will protect the transfer case
from possible damage and will only
allow the transfer case to respond to
one shift per 10 seconds. The
transfer case may stay in this mode
for up to three minutes.
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