Line Level noise 2004 Camry JBL system

[boatbuilder]

I have a 2004 Camry with the JBL syste. I installed a Pioneer DEH-490ib that I got from Nebraska Furniture mart. They supplied me with a wiring harness that has dual RCA inputs on them. I put those into the Front and Rear RCA outputs on the headunit. It works great... BUT I have a very noticeable alternator feedback coming through the speakers. I never had this with the factory head unit. My question is ... is this coming from those RCA connections to utilize the factory amps still or is it coming from the RED constant 12v + wire? I have made sure that the positive power wire is away from these RCA connectors and there is still not difference. Do I need a noise filter on the Power wire or a noise filter on those RCA connections to the head unit?
PLEASE advise.
Thanks,
D

[kurtw]

It's almost guaranteed that your feedback is coming from the RCAs. Try a different harness (Circuit City, Best Buy, etc should have it, or you can get one cheaper online - I've had good luck with the Scosche brand).

You can also cut the RCA ends off the harness and use speaker leads to get signal to the amp, but that can lead to distortion. Make sure your grounds are good as well - some of those harnesses have a factory amp ground (usually black with a white stripe) that needs to be grounded with the radio.