Audio Systems: Car Stereo, pioneer cd player, rca cables

Question
I have no sound coming out of my subwoofers in my car.  I'm not sure exact models on everything, but it's a Pioneer CD player, Jenson 4ch amp,and two 10" Kenwood Subs.  I had the exact setup in one car and switch it to another car(even the same kind of car).  All wires are even the same.  It worked great in the other car.  The amp is on, not in protection, but nothing comes out of the subs.  The only sound I can get is if I switch the filter switch from LPF to FULL to HPF all around, sometimes it will make a very quiet static noise.  I've tried switching the speakers wires all around and the RCA cables all around just to get something, but nothing changed.  If you could help me just get a start then I can go from there.  Thanks, Pete.

Answer
Take a AA or AAA battery and touch it to the raw speaker leads. In other words unhook from the amp amd test that the subs actually do something. They should crackle and thump. Once that's proven to work, reconnect, but only one channel to one speaker at a time. Feed audio signal into the amp from an ipod or something portable. If you have averything working to this point, plug in the headunit's RCA outputs , but only one set at a time. If you get nothing, have the headunit fixed or replaced.