2001 Ford Mustang, Mach 460 Problem

i need some advice on a 2001 ford mustang with a mach 460 sound system heres a list of problems

1. there is no sound from the lower door speakers, there is little sound from the upper door tweeters, and little sound from the rear speakers.

2. the  bass/treble adjustment does not work, the sound seems flat.

3. the built in cd changer will not load any cd's it says full and then shows an error code(not sure what code number)

the car is at a dealership, so i know they wont pay for all day troubleshooting. i need to diagnose and repair if posiible in one visit.

do you think all the problems can be fixed by replacing the deck with another 460.

does anyone know the wiring( powers, grounds, signal...) behind the deck. i found this on here can somone verify its the same as a mustang. https://i13.photobucket.com/albums/a267/ender03/Radio%20Install/fordtaurus1.jpg 

thanks for any and all replies.

-nino.

so i probably need a new oem amp in the trunk, how can i test to make sure the amps are getting power and signal. which amp is for the front and which is the rear. are both amps probably not working. i get no sound in the front bottom, and little sound from the rear. i read somewhere one rear amp is for the rear, and one rear amp is for the front lower speakers. and the front tweeters are internally amped from inside the head unit. can the rear amp problems be caused by the head unit at all, the dealership wants to find a used 460 head unit and they believe all prblems will be fixed.

or they want to install a cheap aftermarket head unit to solve problems. the person that purchased the car wants to keep the 460 system only.

are both amp the same.

can i switch them to see if the problem moves.

are all 460 amps the same from other years.

if removed do you repair them, and can you give a rough cost estimate(idiot)

I am not sure if they have the same exact plugs on the amps.  I have no plugs on my bench that fit them, I have to solder power ground and remote wires to the amp to test them.  They may or may not be interchangeable.  They are in the same case, I just never had a reason to inspect the plugs.  50 to 60 dollars each.  Plus shipping.  They should both fit in a U.S. Postal service flat rate box.  10 dollars anywhere in the lower 48.  One day turn around.  PM me if you need info or references.