I have my Zumo 550 connected to the dedicated GPS circuit on my F800GS. However, when my Zumo's audio is plugged in to my Starcom1 Advance, it creates alternator noise in my communications system. From what I've read, there is a "ground loop" problem, requiring me to take care that the two devices are properly grounded. Furthermore, there is a small spark when I touch the audio plug to the Zumo when I insert it.
I love the convenience of the automatic delayed shut-off of the canbus power. Is there a method to improve the ground through the dedicated circuit? In the alternative, is it possible to use the ground (-) from the battery and the power (+) from the dedicated GPS circuit for the Zumo, and not use the ground through the dedicated circuit?
P.S. I have the identical set-up on my R1200R using the dedicated ciruit on that, and I move the Zumo and Starcom1 from one bike to the other, but no ignition noise issues on the Roadster!