If everything works it must not be necessary in your case. I didn't have the 20 seconds of sound until I connected it. I suspect it is based on your particular components. I had NAV, 6 disc CD player and DSP. I found nothing in explaining what it is for in anything from Seicane.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas