Problem after installing new HU

[PsychoGates]

Ok so I have searched around these forums and have not found an answer to what might be my problem, and so im hoping you guys could help me out.

I have a 2000 eclipse GT with the infinity sound system and recently had a new HU installed. I have never done something like this before and I felt it would just be easier to have the guys at Best Buy install it for me.

Once it was installed everything seemed fine, that is until i began to notice a high pitched faint noise coming from the speakers whenever the car is on. It is always the same volume and doesnt change with the sound of the stereo. I brought it back and the guy said it had to be the amp, but he took it out and changed the wiring a bit saying it didn't need as much power or something and had quite a few wires connected together. Once he was done it seemed like the noise had gone away. However a day later im hearing it again but it isnt as loud, and is much softer.

Ive decided to take a look my self and am wondering if they wired something wrong. I know they used the 70-7004 part. Currently the wires connected from the harness to the HU are black, yellow, red, blue, and blue w/ white stripe. Everything seems to be wired correctly so im not sure if its a problems with the wiring, does anyone have any idea what might be causing the high pitch noise?

Anyway any help would be greatly appreciated!

[Drewski0523]

Blue and white is the wire that turns your amp on. The noise sounds like a ground loop, to determine press the gas and see I the sound gets any louder.

Is it still the factory amp? Are they useing the barrel plug to RCA adapter erosion of the metra harness? If so make sure the RCA plugs are nice and tight. Also make sure the radio is grounded to the metal of the car by the radio as there is no ground in the factory harness.

Pics help

[PsychoGates]

Yes it is using the barrel looking plug to go from the speakers to RCA cables. When i push the gas the noise does not get any louder at all. Yes it is still the factory amp.

I have discovered that when i unplug the front left and right speaker RCA cables from the HU the noise get 10x louder. Im not exactly sure if this tells you anything but it affects the noise.

Also where would the best place to be for the ground to go? Currently they have it screwed into one of the side screws holding the stereo mount.

[Drewski0523]

It's a ground loop and from your description the rca plugs are picking up distortion. You can try grounding them directly. Also make sure they're plugged all the way in.

[PsychoGates]

Ok so what would be the best way to go about doing this? I have made sure all the RCA plugs are in at far as possible.

Is there something i need to do differently with the black ground wire? What do you mean ground the RCA cables directly?

[soundman98]

Originally Posted by Drewski0523

It's a ground loop and from your description the rca plugs are picking up distortion. You can try grounding them directly. Also make sure they're plugged all the way in.

doesn't matter. still a ground loop.. and ground loops are not rca's picking up distortion(none of the wires are long enough for this to be the case), but multiple ground paths with different potential.


i would recommend moving the radio ground first(the metal radio brackets 'should' be ok, but there is a lot of plastic and bolts separating it from a real solid mounting point)-- there is a small metal box behind the radio with a 10mm bolt holding it down-- connect your radio ground to that bolt. that is a very solid metal support for the dash, so it should correct the issues.


also, what deck are you running? a pioneer perhaps?