So, here is what it looks like pre-install.
Just one more relay under the dash, allowing to disconnect the EXI wire instead of grounding it.
Disregard the wire color, I got a 5-pack of cheap relays with holders and they came pre-wired.
In this case, red and white are all grounds.
Yellow is trigger (+12 via switch)
Black is VSC/ECU-side
Blue is Trans/sensor-side.