Vibe SQ12 SPACE subwoofer problem

Hi,
I recently purchased A Vibe Space SQ12 active subwoofer 1000W RMS 3000W Peak. The sub has a built in 500W RMS amplifier. My car stereo has a special subwoofer output. The problem is that when I connect the subwoofer to the subwoofer output it doesn't produce any sound but just vibrations which get stronger and stronger as I push the volume up. If I connect the subwoofer to my front or rear speakers, there is music comming out of it but if I turn up the volume too high the whole system switches off as there have been some kind of overload. The system starts again after I turn the engine off and on again. My car stereo is a Pioneer Avic X1R 4 x 50W RMS.
Any suggestions will be appreciated.
Thank you in advance

 

Hi,
Yes, power and ground wires are connected (otherwise the sub doesn't start at all). At the moment its connected to the front speakers and its producing sound (although the quality isn't as good as it should be ). This setup also causes the whole system to switch off when the sub starts producing too much bass and too many low frequency tones..

 

It has 2 RCA inputs and 2 RCA outputs (as it is an active sub). The RCA cable go from the subwoofer output of the stereo to the inputs at the back of the sub. If the problem is a shortage of voltage, will adding a capacitor fix the problem?

 

thanks for posting me that thread, really informative, even if my problem is a shortage of voltage a cap isn't going to solve it..

 

I found out what caused all the problems, it was the earth wire not being connected properly, the metal bit that it was connected had too much dirt on it acting as an insulator, it all works fine now.. Thanks to everyone for the replies..