Audio Systems: 95 Grand Cherokee Radio/Speaker/Amp, power amp, grand cherokee

Question
I have a 95 Grand Cherokee Limited, the speakers all went out except the front right and the illumination died on the factory head unit.  I replaced it with an aftermarket Sony thinking the head unit was faulty.  I get the same result, only the front right sepaker works, poorly I might add.  I do not have the owners manual so I don't know which fuse powers the amp (but I assume its working since the one speaker works).  Just wondering if anyone else has encountered this problem with a similar vehicle and how to fix it.  Also, when I put a CD in the Sony no sounds come out (not even from the one speaker) I know I encountered this problem when I did my BMW and I don't remember how I fixed it, I seem to rememeber it was a simple fix involving the wiring of the head unit.  Thanks.
-Garrett

Answer
Go to:
http://installdr.com/InstallDocs/Jeep/PDF/533017.pdf

The last couple of pages give wiring diagrams and color codes for your model.

You must check out the wiring carefully.

If you suspect the unit is defective, probably best to pull it out and have it bench tested.  You can do this by yourself if you have wires that you can hook up to your battery and standalone speaker(s) that you can hookup to the unit outside the car.  Once you have determined the unit is working, then you can get the wiring fixed up.

But, additionally, you must determine if there is a separate power amp that has gone bad.  Trace the wiring and look for a power amp mounted somewhere in the car.  In the trunk, under the seats, etc.

Good Luck,
Cleggsan