2010 Buick LaCrosse Owner's Manual - Page 240

8-20 Driving and Operating C (ON/RUN): The ignition switch stays in this position when the engine is running. This position can be used to operate the electrical accessories, including the ventilation fan and 12 volt power outlet, as well as to display some warning and indicator lights. The battery could be drained if the key is left in the ACC/ACCESSORY or ON/RUN position with the engine off. The vehicle might not restart if the battery is allowed to drain for an extended period of time. D (START) : This position starts the engine. When the engine starts, release the key. The ignition switch will return to ON/RUN for normal driving. A warning tone sounds when the driver door is opened when the ignition is still in ACC/ACCESSORY and the key is in the ignition. Retained Accessory Power (RAP) These vehicle accessories can be used for up to 10 minutes after the engine is turned off: ... Starting the Engine Move the shift lever to P (Park) or N (Neutral). The engine will not start in any other position. To restart the engine when the vehicle is already moving, use N (Neutral) only. Notice: Do not try to shift to P (Park) if the vehicle is moving. If you do, you could damage the transmission. Shift to P (Park) only when the vehicle is stopped. Notice: The engine is designed to work with the electronics in the vehicle. If you add electrical parts or accessories, you could change the way the engine operates. Before adding electrical equipment, check with your dealer/retailer. If you do not, the engine might not perform properly. Any resulting damage would not be covered by the vehicle warranty. Audio System Power Windows Sunroof (if equipped) Auxiliary Power Outlet Power to the audio system will continue to operate for up to 10 minutes or until the driver door is opened. Power to the power windows and sunroof will continue to operate for up to 10 minutes or until any door is opened. All these features will work when the ignition is in ON/RUN or ACC/ ACCESSORY.