Help with tucked harness...

Im very confused with this tucked harness…never used one before. So we plug the engine harness and all clips and stuff bolted in perfect after swapping the OBD1 components. So here is where the confusion comes along, this engine harness goes from engine STRAIGHT TO ECU! it does not connect to the body harness on the engine bay at all like the OEM harness does.

As you guys see on the pic above the engine harness is pretty simple. PLUGS to the engine: injectors,alternator,sensors etc… THEN goes STR8 to the ECU. The three small plus on the ecu plugs right into the chipped P28 ecu. I have no idea what plugs into the Black/Purple plug. i dont see anything inside the firewall harness that plugs there??? if any of you guys have any imput please help out.

Also since the engine goes str8 to the ecu am guessing it eliminates the engine bay connection point as the OEM uses correct??? These are the previous body connections the OEM harness plug into…
PLUGS #1 drivers side by firewall these plugs were used with the OEM harness that connected from engine to these. do these get eliminated now?

Here is PLUGS #2 these are on the passanger side next to the Fuse Box. Where do these These plugs goes too? do they get eliminated too???

If any of you guys can help out would be great! Also i notice i have to Run a Wire from the alternator to the fuse box as well. The harness came with the alternator Plug but it does not has a Wire that follows to the fuse box on the engine bay like the OEM harness did.

Who made your harness? Did it come with instructions? Looks to me like something is missing. Typically you pull the main harness back into the cabin and connect it to the tuck harness on the inside of the car. Then the rest of the tuck harness pulls through the firewall and connects to all the stuff on your engine. I’m guessing that there’s some sort of subharness which is missing which connects your main harness to that connector you have circled with question marks.

Yes sir, i already talked to them they forgot to send me the chassy subharness connection… wao #fail.
got me going crazy figuring this out lol…