Adding a Bluetooth Circuit board

There is no external XM module for that radio, the XM receiver is an internal part of the radio that is turned on in software. The only external signal input lines are those going to the aux. jack you already know about. Sorry.

XM Satellite Radio Receiver OEM 28040222 15838797
I have this in my Car.. When I put on the XM the audio goes to this receiver.

That is a satellite receiver only, no audio out from it only the digital signal to the main head unit which is converted in the head unit if you have paid for XM.

This website https://www.discountcarstereo.com/a2d-sts.html says there is a XM Tuner.. I have had it in my hand however, I did find audio inputs by touching the individual wires while listening for the hum.. I found R&L .. However I found a third input and that's where I got confused.. . I wanna be certain before cutting and splicing my Bluetooth in, that I am on the R & L inputs on the Radios 16 pin XM Tuner input. I got those numbers from ebay for reference it looked like the one in my car.. Maybe this is the right one... Its listed as a 2008 STS XM TUNER 20882059

This is the wiring for the individual receiver module. Looks like a gray wire with black stripe is a common audio ground, then a light green with white and light blue with white are the audio signals. Not sure how you will deal with the switching that is controlled by the CAN though.

OMG. That's just what I needed.. I can take it from here.. I had a little electronics some years ago.. I still know how to negotiate a schematic only problem these days is getting the schematics. Bro you just made my day... Thanks a Ton...

Good luck, be careful of the pins though. Sending a voltage pulse into the CAN network isn't a good thing. Let us know if you get it all working. Thank you for using 2CarPros.