Pontiac Montana SV6 2008 Owner's Manual page 106

CAUTION:
{
If your vehicle is facing downward on a steep
grade (15 percent or more), the door may
not stay open and could slam shut, possibly
injuring someone. To make sure the door does
not slam shut, turn on the power sliding door
feature. Then if the door closes, it will close
under the control of the power door system.
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