You have no risk if you remove the BM54 to tinker. Everything else will continue to function. You will not have any audio for the navigation instructions, but that is probably inoperative anyway. Also, all of the radio-related buttons on the left side of the display will be inoperative, but that will not impact any other systems.

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SOLD
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