GMC 1999 Suburban Owner's Manual page 90

The transfer case shift lever is on the floor to the right of
the driver. Use this lever to shift into and out of
-
four wheel drive.
The front axle portion of the indicator diagram will light
up when you shift into four
axle engages.
Some delay between shifting and the indicator's lighting
is normal. If the front axle light does not go out
immediately after you shift out of four
have your dealer check your system.
An indicator near the lever shows you the transfer
case settings:
2-20
-
wheel drive and the front
-
wheel drive,
-
2 Wheel High (2H): This setting is for driving in most
street and highway situations. Your front axle is not
-
engaged in two wheel drive.
-
4 Wheel High (4H): This setting engages your front
axle to help drive your vehicle. Use 4H when you need
extra traction and in most off
CAUTION:
Shifting the transfer case to NEUTRAL (N) can
cause your vehicle to roll even if the transmission
is in PARK (P). You or someone else could be
seriously injured. Be sure to set the parking
brake before placing the transfer case in
NEUTRAL (N). See "Parking Brake" in
the Index.
-
road situations.
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