Finding information and using oem wiring harnesses. and ecu.

I have a pretty basic understanding for the process of making a wiring harness, but what would using the engine's ecu and the engine's wiring harness when engine swapping look like on an older car when swapping the same brand just different car. Tasks would mainly include just powering the ecu to work with the cars ignition and stuff right? I'm looking to swap a 4agze from a jdm ae101 into my 96 Toyota Celica (which is basically a pretty corolla) and I can't find the diagrams for the 4agze. Only early models of the 4agze from mr2s. Any help is appreciated thank you people of the hp academy.

Normal vehicle interface needs to include ECU / Ignition Power, Fuel Pump Relay control. Some ECUs participate in the starter circuit, and then there may be inputs for things like clutch switches to be considered. If the ECU manages a cruise control, there could be vehicle speed inputs, brake switches and control switches.

Typically Factory Workshop Manuals (or good Bentley Manuals) have the wiring diagrams needed.