Chevrolet 2011 Volt Owner's Manual page 396

When you are doing this
inspection, the vehicle could
move suddenly. If the vehicle
moves, you or others could be
injured.
1. Before starting this check,
be sure there is enough room
around the vehicle. It should
be parked on a level surface.
2. Firmly apply the parking brake.
See
.
Be ready to apply the regular
brake immediately if the vehicle
begins to move.
3. With the vehicle off and the
brake not applied, push the
power button to ON/RUN without
starting the vehicle. See
applying the regular brake, try
to move the shift lever out of
P (Park) with normal effort. If the
shift lever moves out of P (Park),
contact your dealer for service.
When you are doing this check,
the vehicle could begin to move.
You or others could be injured
and property could be damaged.
Make sure there is room in front
. Without
of the vehicle in case it begins to
roll. Be ready to apply the regular
brake at once should the vehicle
begin to move.