Audio Systems: 1999 ford taurus radio / amp pnot working, radio tunner, ford taurus


Question
I've replaced both the control unit and the tuner/amp in the trunk, but still no audio, display, nothing. I'm somewhat of an electronics tech, so I tested the wiring harness up to the control unti, ans power seems to be getting there. I've replaced all fuses related. Can you help me please?

Answer
the unit in the trunk is the complet radio tunner amplifier  cd changer controller

the unit at front with the ac is only a tape player and a controller that sends the signal to the the rear
so there is no audio and no display the unit at front is totaly off nothing works from there ?
this unit takes power from the rear unit so all your testing have to be done in the trunk
8 out of 10 is the rear unit  if you change bothe sounds like you are missing power or ground in the back  
it is very easy to bend one of the pins inside the plug when you plug this unit in unplug the unit and check with a flashlight inside make sure all the pins are ok  
there is also 2 powers in the small plug
good luck