So, I added a USB port on my 04 Ultra. I pulled the outer fairing and mounted it in the inner faring. I tapped into the power for the cigarette lighter. Every thing works fine except, when I hooked up my mp3 player to it, I get a tremendous amount of engine noise through the speakers. I'm not worried about that. What concerns me is, will the noise coming from the USB port have any effect on my GPS or when charging my cell phone. I'm not sure if it will make the GPS wonky or mess up my cell. Anyone know? Hope I explained this correctly......

 

You probably have a bad ground. Recheck all of your connections. You may have the polarity switch Orange Positive, black negative. Not sure if it will affect GPS/ charging, but I would fix it right.

 

I used both the + and - from the cig lighter. I'm 99% sure that I hooked them up correct on the USB Port but, I will check again. Maybe I need to use a different ground?

 

I am no techie by any stretch of the imagination, but isn't the USB voltage supposed to be 5 volts? The cigarette lighter voltage is 12 volts. Unless there's a transformer between the cigarette lighter and your USB port, you're putting 12 volts to your devices instead of the 5 volts they were designed for.

 

You might want to try a ground loop isolator such as this one
https://jet.com/product/pdp/78ebd548...lsAaAqlq8P8HAQ

 

Yeah. That.

 

x2

 

If he had 12V coming out of the USB, he would have fried his mp3. USB ports that are made to add to vehicles have a 12V to 5V tranformer built into them.

 

Oh, your right. I don't think I've ever seen one that didn't already have the voltage reducer built in.

For some reason, I was thinking of back when I was wanting to "hard wire" my GPS to my old Street Glide.
That factory adapter that plugs into a lighter socket was too long.

 

did you go by the wiring, or by the cigarette lighter? seems there were some that had the wiring switched at assembly and the hot was going to the ground on the lighter, and vice versa. fried more than a few gps units......