I have a zumo 550 and plug my earplugs in directly via a 3.5 audio extension. I get a background whine/static that only appears when the engine is running. Any help from you vets?
If it's not ignition noice, it could be the mount. All of my static issues were tied to the contacts on the mount. I found that if I pushed or put pressure on the zumo while I was riding it would go away. I called Garmin, they sent me another mount. Trying pressing on it from the top and sides while riding and see if the static changes or moves from left to right channel.
Install a noise filter on the power lead as close to the GPS as you can get. They are cheap, you can get them at Radio Shack and most places that install car audio systems. Typical Noise Filter
It's probably the contacts on the mount. Some people, me included, have had an issue with static or dropouts. I cured mine by removing the little gasket around the base of the Zumo where the pins make contact. Check the Zumo forum. There are several easy cures to try.
If the whine varies in pitch with engine speed, you probably need to install a choke in the power line. Check with your local car-audio installer for an appropriate part. Re-routing the power lead might also help.
The filter is NOT a ferrite. A power noise filter is tuned network based generally based upon an inductor and a capciator, like a low pass filter.
I had posted a link to the Crutchfield website with suggestions up above. Click on the link in my post that says "Typical Noise Filter"
The link in my earlier post to Crutchfield is over kill for a bike, you don't need 15A, but here is one from the Aerostitch Catalog - CLICK ON ME Google is your friend.
I used to do a lot of work with car stereos and if you had a bad ground, you would get a lot of engine noise (high pitch whine that goes up with your RPM's). Don't know if this helps at all. Good luck and post up when you find the problem.
Its the cradle - bad connection between the Zumo and the mount. Get Garmin to send you a new cradle and it will be gone. It starts out like this and then soon you will get complete sound drop outs and eventually it will stop streaming music altogether. I'm convinced that the Zumo is not designed to be repeatedly takei in and out of its mount, and to do so cause the cradle surface to warp ever so slightly when the Zumo is not attached (sun, temperature, etc).
I had a similar problem on my 665 this past week. high speed clicking noise through both the cradle headphone out and the unit's audio out, when the engine was running. when it wasn't running, no clicking. what i did: 1) my cabling was routed underneath the gas tank, on the same side as the fuel pump. I routed it down the other side of the frame. 2) went to radio shack and bought a pack of two snapon RF chokes for $3.19. They are in the drawers with all of the resisotors, capacitors, etc. I put one on the power cabling where it connects to the battery and the other on the cradle cabling's audio out jack. 3) I had originally spliced the zumo's + and - power feeds into a nearby powerlet outlet's feed. I changed that to run the zumo cradle directly to the battery, in an effort to eliminate a possible ground loop. Result: clean sound without any popping or clicking.