So after checking all my wires and deck to check I had no wires shorting out I've
bought a new Apline f-250 to replace my old 3552 which was starting to cut out at random. I used all my old connections which I labeled during removal to make sure I got all the wiring correct. Only thing that was different was the remote wire connection, I put a new one on and set my gains but left my crossovers at the factory settings until I could check both when "setting the amp" Turned it on and I have no sound. Power to the amp but no sound, I can here the speakers when I turn the head unit up to 30 but nothing below that, also my subs would not come on they are run off the preouts into another amp. I've changed nothing and I can't see what I'm doing wrong. Hopefully some one can point out an oversight I've missed. When testing it I had it sitting on a box in the well as opposed to bolted into the well, but the ground was connected so I can't see that as a problem..

 

I know with my alpine head unit, there is a way you can turn the sub on and off. Did you make sure you turned the subwoofer on at the headunit?

 

Check your HU's options for line out modes? I know some line outs are sub only, so if you've got filters blocking low tones from your regular speakers, then it could be that. Or it could be the exact opposite, stopping high tones from hitting your subs, and all you're sending is high tones, which are being blocked.