Subaru 2003 Legacy - Manual (Page 226)

6-2
Interior light
J
Dome light
HS6003BC
The dome light switch has three positions:
ON: The light stays on continuously.
DOOR (middle position): The light comes on when any of the doors (or
the rear gate on the wagon) is opened. The light remains on for several
seconds and gradually goes out after all doors (and the rear gate on the
wagon) are closed.
The light also can be turned on by use of the keyless entry transmitter.
See the “Keyless entry system” in chapter 2 for detailed information.
OFF: The light stays off.
When leaving your vehicle, make sure the light goes out to avoid battery
discharge.