I have a 07 RK and installed the road tech radio about a year ago. I just purchased the Garmin Zumo 550. When I plug in the audio cables there is a buzzing or humming through the speakers. I have done a lot of research on the internet and am determining that it is a ground loop problem. The noise is present with the bike on or off. Any help would be great.

Thanks, Mike

 

Get a jumper wire with clip leads at each end and start jumpering suspect items until the noise goes away. If you don't have internally wired bars, the first place I'd jumper is the riser bolt to tree, and tree to frame. Another common cause is the practice of using a strip of emery cloth on the bars at the riser clamp. This is often done with apehangers to prevent the leverage of the tall bars from twisting in the clamp. It also electrically isolates your handlebars.

 

is the sound present without the Zumo 550 connected? if so then simply ground the back of your radio to a solid ground such as the tree as mentioned above.

if not, then the culprit is your Zumo. I would verify the ground wire in the zumo harness for solidness. Make sure it's grounded somewhere other than tapping into an existing ground wire.