Car Audio/electrical question

[Demo24]

I have a moto Droid that I like to use to listen to Pandora, etc, whilst on the road. Now to get this input into my Subaru sound system I had to go with this mod that piggybacks off of the CD player input (I play a blank cd, hear whatever is input on the jack, neat solution really🙂). This all works fine for most of what I do. However if I plug my phone into charge and try to listen to something I hear this rather annoying 'whine', it's high pitched and sounds sort of like a turbo whistle which increases in intensity as the engine rpms change. It gets pretty annoying after awhile! I like to have it plugged in so the screen stays on for easy song switching without draining the battery. I should mention it doesn't do this in any other car.

Thus I assume this is due to my cars electrical system. Do I need to ground the system or is there something I can buy that can 'clean'(cant think of the right word) the power coming from my 12v output?

 

[effowe]

I did the same thing, see here..

http://forums.anandtech.com/showthread.php?t=2108210

I am having a similar problem, but I don't get a high pitched whine. I get a staticy sound that you can only hear when the volume is turned down and the phone is charging. I think it is some sort of ground loop, but have no idea how to fix it. If anyone has an answer, I would like to know as well.

 

[kornphlake]

it's a grounding issue, either the stereo isn't grounded well or the lighter isn't well grounded, or both.