GMC 1996 Sierra Owner's Manual page 85

To shift into or out of 4-WHEEL LOW (4L) or
NEUTRAL (N):
1. Slow the vehicle to a roll, about 1 to 3 mph
(2 to 5 km/h) and shift an automatic transmission
into NEUTRAL (N), or with a manual transmission
press the clutch pedal.
2. Shift the transfer case shift lever in one
continuous motion.
Don't pause in NEUTRAL (N) as you shift the
transfer case into 4-WHEEL LOW (4L), or your gears
could clash.
Remember that driving in 4-WHEEL HIGH (4H)
or 4-WHEEL LOW (4L) may reduce fuel economy.
Also, driving in four-wheel drive on dry pavement could
cause your tires to wear faster and make your transfer
case harder to shift.
When
your
headlamps or parking lamps are on,
rotate the thumb wheel next to the headlamp switch
up to brighten, or down to dim, your transfer case
indicator light.
Electronic Transfer Case (Option)
If your four-wheel-drive vehicle has the electronic
transfer case, the transfer case switches are below and to
the left of
the
climate control system.
Use these switches to shift into and out of four-wheel
drive. You can choose among three driving settings:
2HI: This setting is for driving in most street and
highway situations. Your front axle is not engaged in
two-wheel drive.
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