This is quick and dirty track car wiring to a switch panel, you'll need the harness pinouts under the dash to wire it in correctly for a street car.
Constant 12V to pin 14, switched 12V to pins 9, 22, 23. This powers on the ECU
This is a JZX90 harness so it might be a little different.
Switched 12V to the two large black wires in the center, there are also two more black wires, they have a yellow and red stripe IIRC. One is the starter solenoid the other gets switched 12V. These wires power the ignitor and injectors.
Finally I used a multimeter to find the coolant temp and oil pressure wires on the harness. The tach wire is the solid black one on the same plug. Find the pinout for the dash plug to wire these in.