Due to a mistake on my part, the version 2.4 Shift Light boards are missing an important trace connecting pins D2 and D8 on the nano. This results in the INTR "Sens" method not operating correctly.
Don't worry: It's an easy fix.
Anyone assembling the DIY kit will need to perform an additional step if you would like to use this functionality. The Shift Light will still function without it, but only on the "Freq" setting under the "Sens" menu option (default).
The INTR "Sens" option enables interrupt, hardware-based RPM sensing. The "Freq" method uses software based RPM sensing. Both methods have been proven effective.
Thankfully this error was caught early enough that NONE of the Assembled kits are affected - the fix has been applied to all previous and future Assembled Shift Light Kits. Furthermore, the error has been resolved in the EAGLE files so future boards (2.5+) will not have this problem.
I'm deeply sorry for any inconvenience this may have caused.
The silver lining: it's easily solved with an additional "jumper" wire between pins D2 and D8 on the nano. When you've finished assembling the kit, before you mount it within the enclosure, simply cut a small piece of wire and solder it to pins D2 and D8 on the top of the Nano (the side with the USB port) which is basically the very bottom of the assembled circuit board assembly.
Again, I'm really sorry about this. It was a minor oversight on my part, and one that I will not make again. I chalk this up to "growing pains" of starting an online kit business -- sometimes mistakes happen. As I said before, I'm grateful it's an easy fix and one that I'm more than confident can be resolved quickly. To reiterate, I caught this error early in the process, and it I've already applied the fix to all assembled boards that have shipped thus far.
I appreciate your understanding.
Jon @ Chippernut