From my site :
The wire I mentioned that you run from the head unit to back to solve the amp not powering on is hooked to #5 on the seicane head unit. Its blue with a white stripe I think. I know its blue just not sure on the white stripe part.
Then the other end of the wire hooks to the “auto ant” wire in the hatch area. It is blue with a white stripe for sure. This will fix the amp problem.
The "other end" is the part in the trunk. So you hook a wire to the #5 wire up front and run it all the way to the back and hook it to the wire in the plug at the back that says "auto ant" on the label (plastic tag around the wire). It happens to go thru the connector directly into the needed wire in the factory harness is why your doing this.