There is a PDF at this link - it should shed some light on the installation...

https://xoutpost.com/974898-post5.html

I've just purchased yet another cable and still- nothing!

So I did your check.

Looks like I've got SW 10 02 42

Does that mean I'm not compatible? If so- what do I do to upgrade the firmware? My radio is SA661.

Here's the pic

http://i.imgur.com/saj9ia7.jpg

http://i.imgur.com/98Fu484.jpg

I think SA661 does not mark the model/version of the radio, as BMW was using this option code from mid-90s, if no 80s, and the radios have evolved since then. The radio models are BM53, BM54, some other models, like CM24 (not sure about the name conventions though, I might be off by a letter or a number).

There is a fellow in UK who knows so much about these radios, you just do a google search for Boris and BMW radio, and his website should come up. There should be enough info about the versions of the hardware and firmware...

EDIT: correction - search for Baris

Carphonics - Car System Repairs and Upgrades

Thanks.

So you're saying my model number for my radio must be wrong?
I used a VIN decoder, which told me:

http://i.imgur.com/RBV5OXA.jpg

As for Baris- this seems like an expensive, lengthy and unenvironmentally friendly option. Shipping my radio from Aus to the UK just to have the firmware updated? Is there no other option?

the option number on the decoder is the order by which factory installs various options. The radio model is a number of the radio device, which is not same as option code...

it's like a paint code for, say black... black is black, code is the same, but over the years, the chemical formula of the paint is changed, and formula from 20 years ago is not same as today...

Ok so could you tell me how to find out what radio I actually have? And what option do I have for changing the firmware (and do I need to in order to use an AUX?)

Ta.

I can see that you have a picture of a 3 pin connector, which is for the cars that have a boardmonitor (with or without Nav), and there is a 3-pin mating connector hidden behind the monitor.

Yours does not have a monitor, so all the connections would be made at the radio itself. I do not know about the radio firmwares and various versions, but assuming that your radio can handle the AUX, you would remove the pins from the 3-pin connector on the cable, and insert the free-hanging pins into the existing connector housing.

Your colors are not factory colors - the factory always uses brown (or variations of brown/other color) for ground, as per German DIN standard.

The Radio determines that the AUX cable has been attached by sensing a 300 kOhm resistance between the Left and the Right channels.

there are only so many combinations for the 3 wires that you have - basically only 3 - the ground wire can be in position 1, 2 or 3. The other two wires, even if mixed up, still would work, either with correct left/right channel, or reversed, right/left channel.

I would suspect that whoever built this cable (from the picture that I saw in this thread), might have used the regular left/right coloring from the RCA cables...

the metal parts of the wires must not touch each other, as they will be shorting the signals.

What is the manufacture date of your radio? from the picture it looks like model CD53, made in May of 2002... in that case, your radio simply might not even have the AUX option... But I don't know enough about the radio variations to be conclusive...

To add to the confusion (and to totally contradict myself!) I've just found a thread where someone with a pre-09/02 CD53, running firmware version 42 actually got the AUX input to work...!

CD53 with SW42 and aux - Bimmerfest - BMW Forums

The quickest way to be wrong is to state something publicly on an internet forum... ;)