I'm sure this has been brought up on a thousand times, but here goes. I am fighting a whine noise in my 2005 Grand Cherokee. It changes with engine speed. I have pinpointed it the the HU, then changed the HU and still have the issue. I have tried to change the ground several times, installed rca gound loop filters which helped a bit. I have installed a inline filter for the power & memory lines-still there. When I have the HU out of the vehicle (hanging by the harnesses) the noise is not present. When I install it back in the dash it starts again. I had installed RFI resistant fabric around the HU and still the same thing.
If anyone has any suggestions I would love to hear them. I had also had the alternator diode's checked which are ok.
Thanks in advance