GMC 2008 Acadia - Manual (Page 113)

Make sure the shift lever is fully in PARK (P) before
starting the engine. Your vehicle has an automatic
transmission shift lock control system. You must fully
apply your regular brake first and then press the
shift lever button before you can shift from PARK (P)
when the ignition key is in ON. If you cannot shift out of
PARK (P), ease pressure on the shift lever, then
push the shift lever all the way into PARK (P) as you
maintain brake application. Then press the shift
lever button and move the shift lever into another gear.
See Shifting Out of PARK (P) on page 2-37.
REVERSE (R): Use this gear to back up.
Notice: Shifting to REVERSE (R) while your vehicle
is moving forward could damage the transmission.
The repairs would not be covered by your warranty.
Shift to REVERSE (R) only after your vehicle is
stopped.
To rock your vehicle back and forth to get out of snow,
ice or sand without damaging your transmission,
see If Your Vehicle is Stuck in Sand, Mud, Ice, or Snow
on page 4-20.
NEUTRAL (N): In this position, your engine does not
connect with the wheels. To restart when you are
already moving, use NEUTRAL (N) only. Also, use
NEUTRAL (N) when your vehicle is being towed.
{ CAUTION:
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless
your foot is firmly on the brake pedal, your
vehicle could move very rapidly. You could
lose control and hit people or objects. Do not
shift into a drive gear while your engine is
running at high speed.
Notice: Shifting out of PARK (P) or NEUTRAL (N)
with the engine running at high speed may damage
the transmission. The repairs would not be
covered by your warranty. Be sure the engine is not
running at high speed when shifting your vehicle.
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