I have a 2000 Expedition EB with the Mach audio system. Was trying to replace the factory HU with an updated aftermarket one for the USB and aux inputs. However, when I put the aftermarket HU in, only the front speakers would work. Everything seems to be wired correctly. I've installed many aftermarket units and this is the first time I've had this problem. Any help would be greatly appreciated.

 

when I did the boys mustang with the mach audio, I'm glad I went through crutchfield......they included a 12v to 5v adapter for the amp....and I think the rears are fed from the amp

 

Actually, as it turns out, the rear speakers don't work with the factory unit either. Nor does the rear audio control, cd changer, or aux power port. So I checked all the fuses and all are ok. Unless there is another in-line fuse hidden somewhere or something? Not even the self diagnostic on the factory unit will work. Only the front speakers and the factory sub.

 

What do you mean by rear audio control? The fader on the OEM radio?

 

I mean the controls on the back of the center console.