I have a 2000 V6 base non-Mach running a Sony HU. The stereo was installed by P/O, with the correct harness adapter, however one of my channel wires to the left front and left rear speaker doesn't make good contact in the harness. Upon inspection, when you plug the harness together, it pushes the wires out the backside of the Metra adapter. Anyone have this problem with these ****ty adapters? I've tried fixing it to no avail, but no luck. The pins won't hold inside the adapter. First time I've had this happen, and I've installed/used Metra adapters for years on various Fords.

 

Ive never used that exact harness, but I haven't had any issues with my harnesses. I would bet that if you call the manufacturer they will try to get the problem fixed.