Transmission Swap. Need help

[Rabrooks]

. I have a 2013 FRS with auto trans. I have purchased a good bit of stuff to perform the swap. I was told I needed a donor wiring harness from the engine bay and from the dash, along with ECU and BCU. Can someone elaborate why I need the harnesses. Seems it would be easier to just add in whatever wiring is missing rather than a full wire swap.

One of the reasons for this question is because I started the wiring swap. Then realized the donor harness doesn't have a connector for one of the components just to the right of the throttle pedal. After investigation of the harnesses I discover there was a running model change to the electrical system. Original system went from late 2012 til 5/13. the new system went from 5/13 to somewhere near current. Guess when my car was manufactured. Yep you guessed it. 5/13.

I would love to get good schematics from both systems if someone can direct me to the best place to get such a thing. Hopefully someone here has a real schematic.
Thanks in Advance
Roger

[Stomachbuzz]

You can always rig up your own 'harness' but it's much easier to use a factory harness [adapter].

The reason you would need the appropriate harness when doing a transmission swap is because the M/T and A/T do not use the same wiring/plugs.

The A/T will have many more plugs for the additional electrics inside the valve body and such. M/Ts typically only have a few plugs for shaft speed sensor, reverse lights, and I guess shift lever position on these cars.

You might think "ok, well, I'll just use the A/T harness but cut off all the unused plugs."

The M/T will have less plugs/connectors than the A/T, but the plugs they share in common likely are not the exact same connectors. Unlikely they will smoothly plug in and you can just tie the excess off with a few zip ties.

You can find the appropriate harness, or you could technically hack your own together just using single wires per pin that you bind together.

[Rabrooks]

Bump for more help
Thanks