GMC Jimmy 2004 Owner's Manual page 87

A (ACCESSORY): This position lets you use things
like the radio and the windshield wipers when the
engine is off. Push in the key and turn it toward you.
Your steering wheel will remain locked, just as it
was before you inserted the key.
CAUTION:
{
On manual transmission vehicles, turning the
key to LOCK will lock the steering column and
result in a loss of ability to steer the vehicle.
This could cause a collision. If you need to
turn the engine off while the vehicle is moving,
turn the key only to OFF. Do not press the key
release button while the vehicle is moving.
Notice: Using a tool to force the key from the
ignition switch could cause damage or break the
key. Use the correct key and turn the key only
with your hand. Make sure the key is all the way in.
If it is, turn the steering wheel left and right while
you turn the key hard. If none of this works,
then your vehicle needs service.
B (LOCK): This position locks your ignition when
the key is removed. The steering wheel locks
when equipped with a manual transmission. It's a
theft-deterrent feature. You will only be able to remove
your key when the ignition is turned to LOCK.
C (OFF): This position lets you turn off the engine
but still turn the steering wheel. Use OFF if you must
have your vehicle in motion while the engine is off
(for example, if your vehicle is being towed).
D (RUN): This is the position for driving.
E (START): This position starts your engine.
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