Chevrolet 2002 Tahoe Owner's Manual page 121

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.
4HI: Use 4HI when you need extra traction, such as
on snowy or icy roads or in most off
This setting also engages your front axle to help drive
your vehicle. This is the best setting to use when
plowing snow.
4LO: This setting also engages your front axle and
delivers extra torque. You may never need 4LO. It sends
maximum power to all four wheels. You might choose
4LO if you are driving off
deep snow and climbing or descending steep hills.
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road situations.
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road in deep sand, deep mud,
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