Chevrolet 2010 Express Owner's Manual page 136

1 (First): This position reduces vehicle speed without
using the brakes. You can use it for major/severe
downgrades where the vehicle would otherwise
accelerate due to steepness of grade. When you shift to
1 (First) it provides the lowest gear appropriate to
current road speed and continues to downshift as the
vehicle slows, eventually downshifting to 1 (First)
gear. The transmission can be held in 1 (First) gear
using Range Select Mode or the shift lever. See Range
Select Mode later in this section.
Notice: Spinning the tires or holding the vehicle in
one place on a hill using only the accelerator
pedal may damage the transmission. The repair will
not be covered by the vehicle warranty. If you
are stuck, do not spin the tires. When stopping on a
hill, use the brakes to hold the vehicle in place.
3-30
Range Selection Mode
The vehicle may have a Range Selection Mode. The
Range Selection Mode helps control the vehicle's
transmission and vehicle speed while driving down hill
or towing a trailer by letting you select a desired range of
gears.