Can you post the part numbers of the components you installed? Also, I am pretty sure that the Sirius module has its own stand-alone antenna, and they are not typically pre-installed in the cars. So, unless you also installed the Sirius antenna, your car may not have one.

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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