1999 expedition rear sub amplifier

I am trying to install an amp in my 99 expedition. I have 5 wires to work with, black-orange, green-purple, red-black, black-green, and light green-black. I have listed below what I have on each and what I beleive they may be.  Please let me know if I am even close on this. Don't want to burn something up.Thanks!

Black-orange= audio (-) 4.97vdc this wire and the red-black are in a foil sheid with a bare steel color wire.

red-black= audio (+).077vdc

green-purple= 7.31vdc No clue? Help!

light green-black= 12vdc

black-green= grd

Are you to replace the amp to the factory sub or installing a seperate one?  An aftermarket will still need a true 12v turn on, it's own power and own ground.  Should only splice in to the factory sub wiring to run a LOC.

Sub (+) RED / Black

Sub (-) BROWN / Orange

BLACK/ Lt Green = Ground

Remote Turn on = Dark GREEN/ Violet

12v = Light GREEN/ Violet

Use a 4 Channel LOC and use the front inputs to get the signal for the rear speakers.  Use the rear inputs to get the signal off the factory subwoofer wires.  Run dedicated power/ground/remote for the new amp. 

Any should work.  Probably pretty cheap if you look online.

I would splice the two rear speaker inputs on the LOC to the factory subwoofer wires.  Then run RCA's from the LOC to rear channel on the amp.  Run speaker wire from your sub to the rear inputs on the amp.

Splice the two front speaker inputs in to your rear two speakers.  Then run RCA's to the front channel of your amp.  Run speaker wire from each speaker to the front channels of the amp.