Putting aftermarket head unit in my sons 2004 Ranger. It has a factory amp and single 8” woofer.

on the aftermarket that clips to the factory harness that runs to the amp, there is one wire I can’t figure out. The wiring diagram shows it going to "fused ignition". The factory wire leading to the factory harness is uninsulatwd stranded wire and shows an inline fuse.

The marching pin on the aftermarket harness is a black and white wire, which the package lists as amp ground. However, this pin is shown as fused ignition when clipped into the factory head unit. I will attach a picture of the schematic and harnesses to better explain.

move get every other connection figured out except this one.

If anyone can help me with this I would really appreciate it.