Toyota Lexusc Owner's Handbook Manual page 452

"ACC" — Accessories such as the radio operate, but the
engine is off.
If you leave the key in the "ACC" or "LOCK" position and open
the driver's door, a buzzer will remind you to remove the key.
STARTING AND DRIVING
"LOCK" — Engine is off and the steering wheel is locked.
The ignition key can be removed only at this position.
You must push in the key to turn it from "ACC" to the "LOCK"
position. The selector lever must be put in the "P" position
before turning the key to the "LOCK" position.
Once you remove the key, the engine immobilizer system is
automatically set. See "Engine immobilizer system" on page
18.
When starting the engine, the key may seem stuck at the
"LOCK" position. To free it, first be sure the key is pushed all
the way in, and then rock the steering wheel slightly while
turning the key gently.
If, in an emergency, you must turn the engine off while the
vehicle is moving, turn the key only to "ACC".
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