GMC Sierra 2005 Owner's Manual page 127

•
While in 4H or 4L you may experience reduced
fuel economy.
•
Avoid driving in four-wheel drive on clean, dry
pavement. It may cause your tires to wear
faster, and make your transfer case harder to
shift and run noisier.
Shifting from 2H (Two-Wheel High) to
4H (Four-Wheel High)
•
Shifts between 2H and 4H can be made at any
vehicle speed.
•
It is easiest to shift the transfer case when
maintaining a constant speed or a slight
acceleration. If possible, avoid shifting while slowing
down, as it will may make it harder to shift.
•
Shift your transfer case lever in one continuous
motion into either the 4H or 2H position.
•
In extremely cold weather, it may be necessary to
slow or stop the vehicle to shift into four-wheel
high until your vehicle has warmed up.
•
While in 4H, your vehicle can be driven at any
posted legal speed limit.
Shifting In or Out of 4L (Four-Wheel Low)
Notice: Shifting the transfer case into four-wheel
low while moving at speeds faster than 3 mph
(5 km/h) may cause premature wear to the transfer
case, and may cause the gears to grind. To avoid
causing premature wear, and grinding the gears,
do not shift the transfer case into four-wheel
low while the vehicle is moving faster than
3 mph (5 km/h).
Shifts into 4L can be made with the vehicle at a stop,
or while slowly rolling about 1 to 3 mph (2 to 5 km/h).
•
Shift the automatic transmission into NEUTRAL (N),
or with a manual transmission, press the clutch
pedal, or shift into NEUTRAL (N).
•
Shift the transfer case shift lever in one continuous
motion into the 4L position.
•
When in 4L do not drive faster than 45 mph.
This will reduce wear and extend the life of
your transfer case.
Shifting In or Out of NEUTRAL
1. With the vehicle running and the engine at an idle
set the parking brake.
2. Place the transmission into NEUTRAL (N).
Shift the transfer case in one continuous motion into or
out of the NEUTRAL position.
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