Noise when engine is running.
 

I have just installed a Tablet in my car as my audio system. I am struggling to eliminate the noise/interference when the engine is running.

The noise seems to be caused by the 12v socket (cig lighter) I am using to power the tablet. When I disconnect the power the noise goes away.

I have added in another 12v socket into the glove box so I continue to use the original one, as well as giving the install the oem look. I thought this was the issue but I have disconnected this but the noise is still there.

GRRRR! I can't figure it out.

bad earth possibly

Tried re earthing it but still there. will sort a multi meter and have another go.