Fuse box wiring no power to ecu(power fc), but car has power?

[Dsmguy1993]

Okay so I have not swapped in my engine yet, but I did hook up my wiring specialties pro harness and interface harness up to my 1989 240sx originally it was an automatic so I noticed when I hook everything up and yes I grounded the engine harness itself and I put the 12v power to the battery source so the harness has power. Anyways my apexi power fc does not light up when I put the car in accessory after I hook it up and im confused. I noticed on my 240sx's fuse box the signal connector has two wires cut from the previous owner could this be why? I also attached a picture of a connector thats just not hooked up to anything does anyone know what it is? Does the engine have to be installed before the power fc will light up? The car itself has power all the windows doors lights etc all work just not the ecu... images below any help is appreciated!:) I have read online and some people say that the power fc needs a specific power source and the stock ecu still runs well so to be honest im at a bit of a loss here I dont know too much about this.

https://ibb.co/26T47XL
https://ibb.co/MkY2Rmg

[S14rebuild]

2 pin connector looks like alternator connector

[Dsmguy1993]

The black one is for the alternator from my fuse box I m almost positive because the two pin connector shown in the pic is not from the fuse box itself its from the body harness near the fuse box actually sorry I should have specified.