BMW PIO Adapters-CD changers

[shogun]

http://www.cambridgebrands.com/1995-540i-cd-changer/bmwpio-adapters.php

[Eric Clark]

Great link shogun! Now I am confused. Is there an aftermarket CD changer that will work with my stock head unit (alpine) and be controled by my stock head unit?

[Cambridge]

Great link shogun! Now I am confused. Is there an aftermarket CD changer that will work with my stock head unit (alpine) and be controled by my stock head unit?

If your stock head unit is the original, it is likely either a CM5901
(mfd by Alpine) or a KE91ZBM (mfd by Pioneer). To verify, press the
(-) and (program) buttons simultaneously on your head unit. The
display will show the radio type. If it says "Alpine", "Alpine2", or
"Alpine3" your radio is a CM5901 manufactured by Alpine. If it says
"Pio" or "Pio2" it is a KE91ZBM manufactured by Pioneer.

If your head unit is a CM5901 or a KE91ZBM, aftermarket Pioneer CDX-M30
CD Changers are often used. A BMWPIO/M adapter cable is used between
the BMW cable in your trunk and the CDX-M30. The cable is made by
Peripheral Electronics, Inc.

The CM5901 and KE91ZBM used Pioneer's M-Bus protocol to communicate with
CD changers. The Pioneer CDX-M series of changers understood this
protocol. Thus, the ability of the CDX-M30 to work with just a simple
adapter cable. Unfortunately, Pioneer's recent CD changers use the
newer IP bus protocol which is not compatible. This is why you see so
many CDX-M30's traded on eBay.

Hope this helps!, :)