ok i have a 90 4cyl mustang and im in the process of putting my 5.0 into it. i bought a 90 engine wiring harness off ebay im almost 100 percent positive it is a 90 because it has a black and grey clip to connect to dash harness and a couple white clips for airbags near mass air and starter solenoid. my blinkers and headlights work but when i go to start my car nothing happens but when i jump the starter solenoid the starter begins to work. i still have the 4cyl dash harness and have read mixed opinions if your supposed to change any wires over for the car to start. any help would be great!