All of these components can boot and do stuff before you turn on the car and after you shut off the car. Therefore, they need power that is independent of the switched ignition switch.

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2000 E38 750iL Highline Edition, Upgraded with the lastest 2006 X5 Electronics
MKIV Navigation, 16:9 Display, Bluetooth, TV/Video with Backup Camera, Sirius, and Aux Input