1) No, the nav computer is the brains of the entire system and controls the screen and radio.

2) There is really no level of irreduceable complexity below the nav, screen, radio, and wiring harness.

The challenge is that the nav computer, radio, and display are all co-dependent. You can not use the old radio with any of the new parts, and the new parts will not function unless all are in place. (Well, the nav and screen will work fine without the radio, but the car would be quiet.)

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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