On mine it looks like the blue connector pin #6 for ibus.

Then 2 and 7 for power and ground.

If those cables are still live after removing the stuff from the back

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Just BMW's - All cars and trucks was two pages long
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1997 528i
2000 323i
2001 X5 3.0 auto
2005 X5 3.0 auto
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Aftermarket E53 Radio Install