GMC Sierra 1999, Owner'S Manual

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yellow blue
2-30
Automatic Transfer Case (If Equipped)
The transfer case switches
are located to the left of the
instrument panel cluster.
Use these switches to shift into and out of
four
-
wheel drive.
You can choose among four driving settings:
2HI: This setting is used for driving in most street and
highway situations. Your front axle is not engaged in
two
-
wheel drive. This setting also provides the best fuel
economy.
AUTO 4WD: This setting is ideal for use when road
conditions are variable. When driving your vehicle in
AUTO 4WD, the front axle is engaged, but the vehicle’s
power is sent only to the rear wheels. When the vehicle
senses a loss of traction, the system will automatically
engage four
-
wheel drive. Driving in this mode results in
slightly lower fuel economy than 2HI.