amp problems feedback coming through sub

I just changed out the shock mounts in my 98' 3-series bimmer so I had to take out my amp and when I put it back together this is what I am dealing with...

My Equipment:

1. Audiobahn 840w RMS amp (sorry not sure of exact model #)

2. Alpine 10" Type R' Sub wired in parallel

Everything worked fine when I took it out now when I put it back in these are my symptoms, I get a constant base tone from the sub something like a feedback sound from a microphone but constant low tone... even with the stereo deck off it does this.  When the deck is on you dont get any music through the subwoofer.So does this mean:

1. My amp is shot

2. RCA cables have interferance coming through them (they are bad)

3.  Sub is shot.

Pioneer radio????

I am having problems with my subs also.   They start to distort / pulse in and out very hard and very slow whenever I turn up the volume on the headunit.  The reason I posted was because I am running a Pioneer Avic D3 and I was wondering what the problem with the RCA is that you are refering to.  I have replaced the RCAs and I think I have a pretty good ground at the Amp.  I also tried a different amp and it did the same thing.  It couldnt have anything to do with the remote wire would it? I am running the D3 with a MTX 4250D amp and 2 MTX 8000s 10"s.  Thank you for your time.  I dont mean to hijack the thread I guess i was wondering if you could tell me what the issue is with pioneer RCA outputs.

Try taking a length of small wire, strip both ends of it.  Ground one end, and touch the other end to the shield of the RCA cable that goes to the amp in question.  If this makes a pop and then the amp starts acting properly, then yes this is your problem.  It is not an easy internal fix on the D3.  This is just as effective and easy to do.   The other end of the wire in this picture needs to be grounded.  This needs to be done behind the radio, not at the amp.    Picture won't upload at the moment  I am going find a thread with the pic in it.

Thank you guys.  I followed the directions and picture sent to me by i am idiot and everything is working perfectly.  My solder job was not as nice as the picture but it is solid and works.  Is this common on pioneer radios?  I love my D3 I now only have 3 complaints the rca deal, ipod interface, and I can barley get it in my truck dash because there is so many damn wires but just minor compliants.  Do you guys usually solder your wiring harness connections?  Thank you agian you saved me hours of trouble shooting and cusing.

Glad to help   Let's see if the picture will upload today.  Just in case somebody else stumbles across this.