Bluetooth odd behaviour

[mihai_stancu]

Hello!

I'd like to ask for advice on future troubleshooting on this issue:
I have a 2003 E85, 3.0i, that has the navigation and cd changer setup.
I have removed the cd changer and navi module from the middle glovebox (I wanted storage space, I was happy to let those go). I've installed an AUX port half a year ago, using pins 3, 4 and 10. Everything works smoothly (apart from the fact that I don't have anything on the pop-up display on the dash). I can reach the AUX mode and just let it there, basically.

As time went by, I came to realize I want a wireless connection, so I bought a Bluetooth adapter from ebay that came with the 3+6 pin connectors. Plugged in where the cd changer was supposed to be, everything went smoothly, it worked just fine.

Because I came to hate the fact that I didn't actually have any display for the head unit, I decided to replace it (since I had no use of the display) with a Business Radio one, which would suit my needs. However, as I did this, I have a problem, the bluetooth adapter no longer works. The symptoms are these:
- I can see the Bluetooth adapter as the cd changer on the radio
- I can pair my phone just fine
- I can control the songs on my phone via the buttons on the head unit
- There is NO sound whatsoever
- The AUX port works fine with the new head unit.

So, in short, the story is that the Bluetooth adapter works with the original, Navi head unit, but it doesn't work with the Business Radio head unit. Do you have any idea why? I could not find anything matching my issue.
Is there anything I could do about this? Is there any coding that should be done?

Thank you very much!