TL;DR Manual harness needs rewired to relay box harness of an auto body, and I need a guiding hand if you have any links/info/walkthroughs.
This is not a topic on the reverse light switch, no issues there. This is relay box harness specific (opposite side of engine bay).
INFO: Car has been swapped from an auto to manual. NA, LHD, new spec engine goodies.

STORY: Recently dropped the engine/trans/subframe unit (as nissan intended) and went through a ton of the external stuffs, including a new harness. As most of you know, they only produce manual harnesses anymore, which wouldn't be an issue, except for my car originally being an auto- the relay box harness does not fit up to the engine harness without some serious rewiring going on. I'm having a horrible time finding anything on this in previous forums, and an even worse time finding pinout/wiring info corresponding to this in the FSM. Anyone have any directions?

Sorry it does not answer your issues, but...

Wiring specialties makes a trans harness for Auto to manual conversions. Plug and play.

https://www.wiringspecialties.com/30altotrha.html

Already snagged that one (albeit from Z1), but thank you anyway haha I was hoping there was some conversion harness between the two parts I'm looking at, but alas

Ok so things worked out really well.

Turns out, the majority of the wiring from the 3rd plug was only for auto controllers, and had two wires that went to other locations in the other plugs. They color matched and everything, so all I had to do was repin/splice the Purple/dot and White/dot wires. Very simple, almost got it to look factory setup. I'll get you guys some pictures sometime, and I'll also be submitting the write up to Z1.

NOTE: I did have to get a computer from a manual Z (number 24, a gen1 manual ecu) in order to make sure the pinout from the harness matched the ecu pinout. However, car runs frickin great now.

Hey, I’m trying to the same thing on my 90 z32 JDM tt auto. I have a manual harness that I’m trying to hook up to the stock auto TT ecu.

How do I do this exactly, because there is that 3rd connector by the fuse box?

Thx