Ok guys. What would the pre-wired sub harness look like if you have one? Is it under the rear seat carpet? Under the kick panel with about 20 wires in a harness? Do you have to splice into that particular harness if you want to install a small powered sub and what wires are they?
Yes, I'm new at this. Can you tell!!!
thanks for all and any help.
2009 King Ranch f150 w/out the premium Sony system.

 

If your adding an aftermarket sub, you want to run new power wire to the battery and find a ground for it where your mounting it at. There is no wire in a car that I would ever tap into to power any kind of amp, regarldless of wattage. What sub are you adding?

 

KENWOOD KSC-SW10 DUAL 5x7 POWERED CAR SUBWOOFER SUB

 

I have the Kenwood KSC-Sw1 powered sub and it came with the harness and all you have to do is plug it into the box and then run your wires accordingly. Was a pretty quick install, granted I have an aftermarket reciever and I'm gonna bet you have to do a little more wiring to get it to work with the factory system. Doesnt sound bad at all IMHO, not crazy loud or anything but I'd compare it to maybe a notch or two above the factory premium sub system in these trucks.