GMC 1999 Savana Van Owner's Manual page 91

DRIVE (D): This position is for normal driving. If you
need more power for passing, and you're:
D
Going less than about 35 mph (55 km/h), push your
accelerator pedal about halfway down.
D
Going about 35 mph (55 km/h) or more, push the
accelerator all the way down.
You'll shift down to the next gear and have more power.
THIRD (3): This position is also used for normal
driving, however, it offers more power and lower fuel
economy than DRIVE (D). You should use THIRD (3)
when carrying a heavy load or driving on steep hills.
You should use THIRD (3) (or, as you need to, a lower
gear) when towing a trailer to minimize heat build
and extend the life of your transmission.
SECOND (2): This position gives you more power
but lower fuel economy. You can use SECOND (2) on
hills. It can help control your speed as you go down
steep mountain roads, but then you would also want
to use your brakes off and on. If you manually
select SECOND (2), the transmission will drive in
SECOND (2). You may use this feature for reducing
torque to the rear wheels when you are trying to start
your vehicle from a stop on slippery road surfaces.
FIRST (1): This position gives you even more power
(but lower fuel economy) than SECOND (2). You can
use it on very steep hills, or in deep snow or mud.
If the selector lever is put in FIRST(1), the transmission
won't shift into first gear until the vehicle is going
slowly enough.
NOTICE:
If your rear wheels can't rotate, don't try to
drive. This might happen if you are stuck in very
deep sand or mud or are up against a solid
object. You could damage your transmission.
-
up
Also, if you stop when going uphill, don't hold
your vehicle there with only the accelerator
pedal. This could overheat and damage the
transmission. Use your brakes or shift into
PARK (P) to hold your vehicle in position on
a hill.
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