well then id be trying a different amp.... if it still does it then its something with in the wiring/car

 

Sounds like your RCA connection lost its ground point... is you HU a Pioneer? If it is there is one other thing to check if the following do not work.

connect a small wire from the RCA ground (the outside connector NOT the inside pin) to ground if you lost the signal ground then this should stop the switching noise. This is also how a bad solder joint in an RCA sounds but since you tried a different RCA I do not think the wire is bad, I think the ground on the signal cable is bad.

Also double check that the wiring from the amp to the subwoofer is clean and no leakage to ground.

Double check the HU connections to positive and negative as this can introduce noise as easily as the amplifier.

 

no its a alpine
I'm going to try that in a bit.

 

Tried putting the rca outpin to a ground and no difference. Going to check the wires to the sub and re wire the power and ground wire on the HU in a bit

 

OK found the problem, Turns out the main OEM audio harness is all ****ed up. IT's hacked up from the previous owner, looks like he was too cheap to buy a god damn harness so he cut up the facotry one and ran wires from it. I was moving the harness around and at one point it kicked in and it was playing but not at full potential and its just making noises when i move it like wires are touching. Now i have to re wire them thanks to the previous owner. thanks guys

 

interesting symptoms, very deceiving problem and you did a good job troubleshooting this yourself too... the boys got skills

I had the same problem when I had a Concord cassette HU, heck that was before indoor plumbing

 

LMAO. I don't think I was alive when people still used cassette HU's lmao. Well okay, I was like 9.

Glad you found your problem man.

 

never mind ,re wired the harness and still same . i narrowed it down to the amp im gonna test it on another amp now.

 

When you rewired, did you run a new ground right to chassis for your HU?

 

to the chassis.
changed amp and now it works fine. so it was the amp the whole time.
opend up my amp and i find that the pin inside the RCA input is rammed though it so it wasn't making contact to the rca cables to my HU. I don't even know if this amp is good anymore. I pushed it back in now im gonna see if it works.