Interesting, would like to know too. On the one hand the head unit, garmin and remote might be tied together. You might be able to replace the head unit and get a connects2 for the remote. Then again the garmin might just be another aux in to the head unit. It's the remote-head-garmin linkage where it might come down to proprietary signalling.
Sent from my Nexus 4 using Tapatalk