GMC 1999 Suburban, Owner'S Manual, Page: 91 / 424

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NEUTRAL (N): Shift to this setting only when
your vehicle needs to be towed or when using a
power take
-
off.
4
-
Wheel Low (4L): This setting also engages your
front axle to give you extra power and also gives you a
higher driveline ratio. It should be used only for
off
-
road driving.
You can shift from 2
-
Wheel High (2H) to 4
-
Wheel
High (4H) or from 4
-
Wheel High (4H) to 2
-
Wheel
High (2H) while the vehicle is moving. Your front axle
will engage faster if you take your foot off the
accelerator for a few seconds after you shift. In
extremely cold weather, it may be necessary to stop or
slow the vehicle to shift into 4
-
Wheel High (4H).
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 the transmission into
NEUTRAL (N).
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 and run noisier.
When your headlamps or parking lamps are on, rotate the
thumbwheel next to the headlamp switch up to brighten or
down to dim your transfer case indicator light.