I installed a new HU yesterday and all seemed fine. Then this AM I notice I'm getting alternator or drivetrain whine when using the AUX input w/ my Sirius radio. Since I can't improve the grounding in the harness what can I do about this? I should mention the RCA's are plugged in and lying on the frame of the transmission housing right now. The RCA's do have some exposed metal so there far from isolated...

 

if you are useing cigarette lighter for power source for Sirius radio, you can try to improve the ground between cig lighter and deck

My experience with mp3 player was noise when useing cig lighter for power, no noise when i use self contained battery in mp3 player.