Alright, so I traded my sister head units, clipped all the wires from my harness and the ones from hers and then re-attached them all. Listened to my old deck in her car which is a pioneer and it sounds fine and all the speakers work and all that. Then I put hers in my car which is also a pioneer and then when i go to turn it on i start getting background noise, you can hear the cd spinning through the speakers. Its pretty loud and very much affects the sound quality. And as im driving the RPM's also affect how loud the noise is.
Is there any way to fix this? I dont understand how this could of happened by using the exact same grounds and positives. I did make a video of it if it is easier to understand.
My sub and door speaker amp are on the same set of RCA's by the way.