Are there extra plugs by the ECU? Ive never taken out a harness but the wires could be everything else under the hood including the wires going to the headlights turn signals etc etc. Get some wire colors and wire sizes and compare them to the TEWD online here and see if the wires match the wiring diagrams.
http://www.cygnusx1.net/Supra/Librar...x?S=Main&P=002
There is going to be some differences between the turbo and NA.
Im not sure about the fuse box in the engine bay though.