Hi,

I have a 2004 Z4 (E85) with Navigation (HIGH).  It has steering wheel buttons for phone connections but doesn't seem to have a TCU mounted.  I'm trying to hook up a cheap BT stick and want to connect the steering wheel buttons. However, I don't know how to connect the wires.  I don't have an Electronics background but recently been learning and doing some fun projects with Arduino.

I was planning to get a cheap BT stick, rip it off and connect with the factory radio. I bought something like this https://www.amazon.com/gp/product/B075DFSLSV which has the ability to connect phone and stream the audio to AUX. I now want to rip this and connect the steering mic and other buttons to my factory radio. Mic is the most important thing but I'll be interested in connecting the Call and R/T buttons too if possible so I can make real handsfree solution without touching my phone and make use of the factory display.

I also got this https://www.aliexpress.com/item/2016...694897779.html which I could use if that works better.

I know GROM or MediaBridge will do it and they are not that costly like the factory TCU but I wanted to do this on my own.

Anyone who can guide me with the wiring for this?

Thanks in advance.

Ravi.