Originally Posted by Pacemaker1000
Looking a the diagrams you kindly posted, assuming all garmins output the necessary signals, then it should be possible to rearrange the b1-b12 connections if they are not in the correct order?
I am not sure if it's that easy - I am not even sure if the regular Garmins output the necessary signals (in particular the "mute" signal) at all without modifications. I have found (but not completely studied) this thread
in another forum, lateron also referring to the pinouts for Nuvi 7x5 and 8xx. Unfortunately almost all relevant pics that could have enlighted the coerrect pinoputs have been removed by the mods due to size issues or from external upload servers. Nonetheless, you will find useful information, e.g. on page 13 to 16 (look for "managed port devices" - maybe BMW has an own id only implemented in their devices) and on page 17 a hint that a "mute" signal is most probably not implemented in regular Garmin devices.