The OEM tach had a shift light built into it, it works independently of the tach and not wired to it in any way and/or worked as a mechanical shift light. It's simply the shift light bulb with housing built into the tach housing (convenient to have RPM and shift light next to each other), however tracing the wires only the ground was plugged in, and the source lead (to have it turn on) was just dangling as the bike had been screwed with.
In other words, I'm trying to locate where the shift light would get a lead to inform it to turn on when it got into the high revs.