Project Ruze The UK's first all-Japanese RX7 V8?

Transmission Wiring

It’s like Mazda knew I was going to do this. All the wiring for the transmission is held in one plug (referred to in the Mazda docs as connector X-11) which is behind the heater matrix. It looks like this:





This plug has +ve and -ve for the speedo signal to the dashboard, a +ve ignition feed and a wire to the rear lights for the reverse light switch, a big ground the instrument cluster needs for all its sensors (and without which the odometer will not show a reading) and a wire for the water temperature sender. It’s all documented on this VERY useful site:

So, it’s trivial to make a loom that just wires this up to the gearbox. Except you can’t do that, because a Toyota speed sender (or VSS in Toyota terms) won’t interface to a Mazda speedo head. So, you need one of these badboys to sit between them and convert the pulses.

To make a wiring loom to link all these up, I used original plugs from Toyota. I couldn’t get the other half of the X11 plug from anywhere, so I replaced it with my own 6-pin connector. Using info from this site:

I ordered the plug and pins for the speedo sender and the reverse light switch from my local Toyota:

1 x 90980-11143 (VSS Plug to fit R154 sender 83181-24060)
3 x 82998-12440 (pins for above)
1 x 90980-10575 (Reverse / back-up light plug to fit R154)
2 x  82998-12270 (pins for above – note part number in photo is wrong)

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This is how my loom goes. I run it completely internally in the car, and made a hole through the transmission tunnel just before the dashboard ends, to keep the wiring tidy and not visible. I’d like as little wiring in the engine bay as possible. It goes like this:







I mounted the Dakota SGI-5 next to X-11 – in hindsight I would do this differently as you have to be able to get access to it to calibrate it with 2 small microswitches. However it’s not the end of the world, I’ll just do the calibration with no heater matrix.
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Best thing about all this was it worked first time 😀


I'm the one actually trying to build this thing!