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Pioneer CD-BB92 Adapter

CD-BB92 Adapter
CD-BB92 Adapter
(click to enlarge)

From 1989 into 1994 BMW used Pioneer CD changers in several applications. These changers used Pioneer's M-Bus (not to be confused with Alpine's M-Bus). Of course, when BMW rebadged the CD changers they tweaked the cable connector pinout a bit.

From 1989 into 1994 BMW used radios with built in CD changer controllers manufactured by Pioneer and also by Alpine. Alpine's BMW radios also communicated using Pioneer's M-Bus cable and protocols.

Eventually, Pioneer discontinued manufacturing devices using the Pioneer M-Bus protocol and replaced it with their IP-Bus protocol. The CD-BB92 adapter is designed to allow M-Bus radios to manage IP-Bus devices.

I was curious to see whether my stock BMW radio (manufactured by Alpine) could control Pioneer's latest IP-Bus creation. So far, unfortunately, I haven't been able to make this device work in a BMW application. My test case was with my stock BMW CM5901 (Alpine3) radio. Using a BMWPIO adapter, a CD-BB92 adapter, and a Pioneer CDX-P686 IP-Bus CD changer, I set up my lab as follows:

CM5901 <==> BMWPIO <==> CD-BB92 <==> CDX-P686

The CM5901 recognizes an M-Bus device is attached when the CD-BB92 is linked in (whether or not the CDX-P686 CD changer is attached). However, the CM5902 cannot access the disks inside the CDX-P686. Moreover, the CDX-P686 recognizes an IP-Bus controller as being online when the CD-BB92 is linked in (whether or not the CM5901 is attached).

CD-BB92 Packaging
CD-BB92 Packaging
(click to enlarge)

Thus, it seems that the CM5901 radio has some limited communication with the CD-BB92, and the CDX-P686 changer is also having some limited communication with the CD-BB92. However, the CM5901 cannot seem to fully access the CDX-P686. My guess is there is some translation failure in the CD-BB92 adapter. Perhaps the CM5901 radio (by Alpine) is not fully adhering to Pioneer's M-Bus standard, or is in some other way tweaked.

It would be interesting to retry this test with Pioneer manufactured BMW radios such as the KE83ZBM or KE91ZBM. Perhaps the Alpine manufactured CM5901 is not as true to the Pioneer M-Bus protocol as required by the CD-BB92 adapter. Unfortunately, I no longer have the CD-BB92 adapter. However, if anyone gets it to work (or not) please feel free to drop me a line and I can add your findings.

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