Fatcory amp wire colors

I am working on a friends 1998 Ford Escort "Sport" which has the factory amplifier under the front driver seat running the front and rear speakers. I was looking in the posted materila and it does not address the OEM wiring on the factory amplifier. If you could please post the INPUT LEADS BY COLOR I would greatly appreciate it. My problem is that the owner is a cheapo bastard and won't buy a new head unit w/ RCA'a so i'm having to run the amp off line level inputs from the head unit. However, the factory amp is keeping the system from working properly i suspect because the aftermarket MTX amp he has won't accept amplified/x-over signal from the factory amp. Thus I plan to get sugnal from before the amp I just need to know which of the leads on the smaller plug (the input i think) are power/gnd/and most inportanlty, SIGNAL .Any info on this would be appreciated.

~CJ  

hope this page helps https://www.installer.com/cars/ford.html theres wire info on the bottom of this page