Toyota Prius 2011 Manual page 377

To prevent 12 volt battery discharge
■
If the interior lights and personal lights on when the door is not fully closed or
the interior light switch in door position, the lights will go off automatically
after 20 minutes.
Customization that can be configured at Toyota dealer
■
Setting (e.g. The time elapsed before lights turn off) can be changed. 
(Customizable features P. 596)
3-4. Using the interior lights
3
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