Audio Systems: Radio install on a expedition, voltage measurement, aftermarket radio

Question
I am trying to install an aftermarket radio in a 1997 Ford Expedition.  I bought the wiring harness for the factory plugs.  The problem is that I have no sound, I am assuming that it is a problem with the factory amp not turning on. I am an ASE master tech so it is not like I am an idiot when it comes to cars, but boy do I feel like one now.  Thanks in advance for any help.

Answer
Go to the bottom of this long page for a study of the wiring, color coding of the wires, etc.

http://www.installdr.com/InstallDocs/FLM/PDF/356033.pdf

Take a voltage measurement on the power lines with your vom and make sure the amp has power.

I think you will find the problem. And it will likely be the wiring harness has a wrong connection.

Good Luck,
Cleggsan