Sorry if I missed prior references to US mode and OS V26. Both of those are where you should be. So you you got me. I thought that I had a silver bullet.

If you CDC is making noises when you push MODE, that means that your Sirius module is connected correctly, because the CDC gets its power and I-Bus signal from the Sirius module. You tried two different radio modules that both support Sirius, so you can eliminate that. I would focus on your nav computer...

What is the SW number on the label on top of your nav computer?

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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