I am going to assume that the Ford amp is wired to the speaker inputs in your factory harness. Now, you tried adjusting the gain on the amp and it did not change the volume of the sub at all, correct? Did you check your deck to see if it has a preamp adjustment like volume or the ability to turn the preout on and off?

 

yeah its hooked up threw the factory wiring harness, the gain made a difference but not much at all, i checked my deck for preamp adjustments but there are none, i check the manual aswell states nothing about them

 

You have really kinda narrowed it down to there actually being a problem with one of the three. Again, if you are sure you have good power for the amp and assuming all your connections and cables are good, there has to be problem with the deck itself, the amp, or the subs. There really does not seem to be anything else. Again, I would double check all the connections and make sure no wires are shorted out and that your power and ground wire are big enough. If all connections and wires check out, it has to be one of the three components.

 

but see, i dont think there is a problem, the situation is my deck does not have any preamp outputs for subs, my subs r fine i know for a fact and my amp because i disconnected the front and rear speakers and blasted it and it gave enough power to make the speakers very loud of course this would make the other speakers blow because all of the volumes on all the speakers are being turned up at the same time, when i get my new deck everything should be fine as long as that has the sub preamp outputs

 

You kinda answered your own question right there. When you have the Ford amp hooked up, your front and rear speakers play loud but, your subs do not. When you unhooked the Ford amp, you can turn the volume up and your subs play fine. You have a gain problem between the Ford amp and the Kingwood amp. You need to figure out a way to turn the Ford amp down so that the output of your front and rear speakers match the output of your subs.

Also, your rca preouts do not have to be dedicated sub preouts. The preouts pass a full range signal and whatever you hook it up to can cross over the signal for high pass, low pass or whatever you need. Unless the head unit has a built in crossovers and dedicated front, rear and sub preouts, any preout can be high, low or sub. It depends on what you do with the signal after the it comes out of the deck.

 

no but see, i never unplugged the ford amp everything works the way its supposed to, the problem is that you cant control the output of my subs from my deck, so i cant turn ONLY the subs up and leave all the other speakers at a set volume, theres my problem, so im going to buy a new deck, one that has front, rear, and sub preamp outputs, this way i can control each set of speakers seperately

 

You are correct. The only way to adjust your subs is at the amp. The new deck would probably solve your problem.

 

thank you everyone for all your help! it taught me alot, im going to buy a new deck and i'll let you guys know how that goes