DIY: FRS Tachometer signal and Healtech shift light install
 

The documentation on how to get a tach signal is sort of all over the place on this forum, so I figure I would consolidate it here.

1. (Optional) Remove the front passenger seat by removing the 4 E-10 bolts and disconnecting the airbag harness and occupancy sensor harness.
This is entirely optional, but makes accessing the ECM module and soldering the connection much easier.

2. Determine which wire to tap
The easiest wire to tap for the FRS is, IMO, A36: PIN 10: RED AND YELLOW WIRE. This is the bottom connector on the ECM module on the passenger side right leg foot well. Apparently, BRZ drivers also have a dedicated tach signal on A35:PIN 15. For the BRZ, if there is no wire there, apparently it's possible to simply stick a pin in that connector to get the signal. However, I can't vouch for any of this.
https://i.ibb.co/1vT06GV/combined-wiring.png

3. Connect Power Source
Use fuse taps to hook up the shift light to Accessory and Ground.
https://i.ibb.co/0cYDJst/FUSE-DIAGRAm.png

4a. Peel away the black harness protective cover to expose the wire
This can be peeled off without damaging the protective cover and reattached when splicing is done.
4b. Splice signal wire and confirm tachometer signal
I used an xacto knife expose the copper core, and connected the shift light signal wire to the core with an alligator clamp. I then connected to the Healtech unit from my phone via Bluetooth, went into settings, and was able to confirm a live tachometer signal.
4c. Solder connection
Once signal is confirmed, I then stripped the connecting wire about 2 inches, made a loop over the exposed copper, twisted the loop tight, and soldered and taped the connection.
https://i.ibb.co/dJvFgmw/splicing.png

5. Enjoy heightened RPM Awareness
The Healtech Shift Light Pro is nice because it is very small and Bluetooth programmable to custom light colors and patterns at 3 custom RPM levels. I've found that color is much easier to recognize peripherally than the usual number of dots lighting up. The RPM read by the Healtech unit is half of the actual RPM, so I had to set my shift points accordingly. I ended up attaching the shift light to the center of the analog tachometer.
https://i.ibb.co/KNqxMKJ/installed.png

Thanks for this!! I am going to tap into the R&Y wire (A36 pin 10) for a Modifry shift beeper. I had it on my S2k and really miss it for the twin. Fingers crossed it works.

Thanks again for posting this info. Worked perfectly!!

Finally got around to installing the Modifry shift beeper. I wouldn't have figured out the coil trigger myself. Here are two videos with the beeper from this past weekend. Set for 3 beeps at every 200rpm before redline.

http://www.youtube.com/watch?v=uQJyzsyY87s

http://www.youtube.com/watch?v=X2fmM2nBxkA

Is there a way to rice up this technology? Maybe connect it to the footwell lighting.

arduino!

Can you install a small screen and instead of a light it'll pop up "DANGER TO MANIFOLD" when you need to shift??

there was someone that replaced the clock display in our cars with a screen and and arduino with an OBD reader. lots of work.

Looks (and sounds) awesome man! Glad I could save ya some time.

Loooool do it. I have to shift light set to flashing pink and blue at 7k so it's a e s t h e t i c. But what you're describing sounds way more involved.

Super Helpful! I purchased the Ecliptech P2 Shift light. If the car is below 4k, there are not lights, so I know I'm out of the power range. Just need to wire and mount it up!

https://ecliptech.com.au/shift-p2/