No idea, mine is a 2006 Model with a business radio module.
The wiring diagram is available in this thread, you can clearly see the labelled pin outs.

Isn't there a time frame limit on these radios as to what ones are and aren't capable of aux input?

Maybe you should be retracting the 1999-2006 comment then, because from what I understand, it's not the range of the overall range in which this vehicle was made but more importantly the revision date/version of the software on the radio itself.

that was a reason i asked in one of the early posts for the date of the car built - according to the WDS the AUX is available from 09/2002 production...

there is also an issue with round and flat pins on the radio...

however, from what i remember, if the radio is acting up and you send it out to Baris in UK for repairs, he can flash/install/activate/update the old radio to have an aux...

search for Baris on this forum and on the bimmer forums, there should be more info about this...

I'd love to have the option of adding aux for $5, $10, etc but I'm not trying preserve the interior by any means. When the price outweighs aftermarket options ($100 gets you a decent BT stereo with more power than the stock stereo...and probably better reception) I stop entertaining mods like this. I'm sure shipping back and forth would outweigh the gains.

I went full aftermarket in my first X5...AVIC F90BT, ran RCA's to a sub amp, fiberglassed the stock enclosure to fit a 10". I want to do it again, I'm just hoping for a cheap alternative until I get off my ass lol

Ah, i see what you mean...
Well, it works in the 2006 with BM53 module
I did the software update myself ages ago, no idea if that made any difference though.

Initial post has been edited, sorry for the confusion.

I emailed Baris to see if he'll give instructions on how to update the software, assuming it's something I can do w/ my Dell GT1 style laptop.

No apologies, I just got all excited thinking I could finally do this vs buying a $100, used, 13yr old stereo because for some reason everyone still wants all the money for these things.

There are some other ways to get where you want to go. One is from Grom, another is the Audiovox mediabridge or the Dice/Audiovox silverline. Grom and Silverline are between $80-100 on Amazon. The mediabridge at about $150. I have the mediabridge. The mediabridge provides BT, AUX, USB and satellite radio as an addon if you want. It uses all existing radio and steering wheel buttons. All are available on Amazon.

So the factory Bluetooth is deactivated or ?..everything goes thru the media bridge?did you do the install yourself?i was thinking to buy the 70$+ aux cable from ECS but better pay more and have them all
Is this upgrade worth it if I'm looking to get the Dynavin N6 in the next few months?
Just asking cuz I don't have too much imagination on how electronics work and how they're connected..

I don't have factory bluetooth. I don't know the answer to that question. Yes, I did the install, not difficult, great directions and great technical support at least at that time (several years go). It took a about 4 hours because my CD player was in the rear. It has worked flawlessly, well worth it. The Dynavin was not available then. I have looked at the the Dynavin. For me it doesn't offer enough value. I would go that route if my radio failed. I suggest you weigh the benefits of each against the difficulty and time it takes to install each. If I were going to a Dynavin in a few months I don't think I would do anything. I would save the money and go to the Dynavin sooner.