93 mr2 ground issues

well ive got a 93 mr2 turbo that ive done a basic upgrade on; deck (pioneer 760mp), type r components and a concept amp. when the speakers are powered by the amp im getting a buzzing (ground loop) from them, keep in mind the car is off, the key is turned to the acc position. ive done the "big 3" and the problem persists. power and signal wires are nowhere near each other. here's what ive seen in the car, there is a solenoid in the car that makes a faint buzzing sound that seems to be the same pitch as the sound in the speakers. i will definately need to check the ground on it but will it create "ground noise" even if its grounded properly? once the car is started the noise is louder than the music comming from the speakers, and the gain is set to about 1/3 right now. and lastly would grounding the rca's help, and do i need special rca's to be able to ground them? so after searching several boards this appears to be a common issue with mr2's with power steering but no one posts how it was fixed. thanks for taking the time to read about by prob....

That relay could be causing a feed back through audio rca's but definately don't ground the rca's.  Pioneer have a design flaw in the rca preout circuit, this usually causes alot of problems because they tend to blow the "earth track" inside the head unit it self.  Try a ground loop isolator but it may not work if the unit has already blown. WOW Sight and Sound

Maroochydore

Nothing is impossible!

Do it right the first time or don't do it at all.

This guy here used to own a 93 MR2 turbo with zero noise in it. Replace the cd player as it is more than likely the source of the noise problem.Top Secret, I can tell you but then my wife will kill me.

is it possible that pioneer hu's suck. i tried my older premier p900 and i got the same noise, and it sounds like mad550 knows something about the internals. the unit will still work with just the 3 wires hooked up to it (gnd,acc,12+) without having the case grounded with being installed so i dont know if the "earth track" has blown. i tried an isolator and it made the audio sound wavy like i was listening to it under water. the audio place that sold it to me sold me one for video, will that make a difference? thanks.