Sub won't work!?!?
 

I hooked up everything last night to wire up my amp and sub, amp turns on but nothing is happening on the sub side.
Ground is good.
Rca's are good.
Remote wire and 12v battery wire are all good as well.
Speaker wire from amp to sub is good (works in other car)
What am I missing?

Do you have a inline fuse for the 12v's

All fuses were good. Battery amp n inside dash fuses. I'm running out of ideas. Not sure what else would cause the problem

If your car had the premium sound package there's an amp under the driver's seat you're going to have to wire around.... or was it under the passenger seat?

Are you using the stock wire harness?

The guy that put the new engine in ran a new harness. What made it a premium sound package?

The premium package went through a couple evolutions, but basically there was an external amp which was integrated with the upgraded head unit, and the car had 2 (or more in later models) additional speakers.

I'm going to go out on a limb here and suggest that the guy who worked on your engine only put in a new engine harness not replacing all 7 (or however many) harnesses there are threaded all across the car.

Look in the TEWD and look in your car for an amplifier.

Yes just the engine harness and I have like six speakers n the car so it might be. And the amp would b hooked up with the head unit anyway right? If I was to solder the radio wires directly to the stock wires would that bypass it? I will check out the wiring diagrams n see what I can come up with. What does the amp have to do with the subs not hitting?

Oh, sorry... So the rest of the system works, just not the subs? Does the amp have a signal line and if so, did you remember to connect it and is it the right signal type for the deck's trigger (positive or negative)?

I hooked up 2 different head units with sub outputs with neither of them working. Both had setting for amp install and sub settings. (I didn't have to manually set up anything for the amp or sub to work with the head unit) The only thing I can really think of is something in the stock harness that is making it mess with the rca's or something to that extent. The only other thing I can mention is that the right front speaker goes in and out on occasion. (not sure if that has anything to do with it or not)

And the signal wire (remote wire??) yes...I hooked it up to the stock power antenna wire...(sub will only hit when radio is on, NOT CD, AUX, and etc...)

With much more specific info no one is going to be able to do a lot more than guess (unless they want to cover an install from scratch... I haven't the patience). Where is the Amp getting power? Have you verified it is getting power and enough current? Does the amp have a remote/signal line? If so is it connected? If so do you hear the amps power relay kick over when the remote signal is given by the head unit? Do the head units' settings have the pre-outs turned on by default? Running wires to the Amp is nothing, if you couldn't manage that you should be changing light bulbs so I doubt that's the issue. Is the amp well grounded to a bare metal location which isn't isolated by paint?