Hello. I’m a university student in Japan who recently started customizing Daihatsu cars. I own a Cuore that I’ve swapped with a K3-VET engine from a YRV by myself.
Right now, I’m trying to build a center tachometer-style speedometer, and I’m analyzing the binary algorithm of the EEPROM in speedmeter. However, I’m stuck because I’m not very familiar with programming.
Out of the 128 bytes of data stored in the EEPROM, I’m trying to find out which parts manage the odometer, as well as the coefficients that control the needle movements for the speedometer and tachometer. I’d really appreciate it if someone could tell me where those values are stored and how they are converted and saved.
Sorry for my poor English. I look forward to your reply, and thank you for reading.
Welcome.
Your english is very good.
I don’t know if anyone here can be of help with that as there are very few that look into the daihatsu ecu’s.
I have only really known of one person years ago that played around with them.
Hopefully someone is able to help.
Something else to consider is using some diagnostic software to pull the data from the OBD2 port? A lot of low cost/free diagnostic software will allow you to pull the speed sensor data and graph it on a laptop/tablet, so working backwards from there might help to isolate it.
Were you looking to build an analogue or digital centre speedometer? Because a digital one would likely be substantially easier to create using a feed from the OBD2 port.
In my experience, the speedometer reading will be taken from the hall effect sensor in the ABS, with readings taken from multiple wheels and cross-checked to make sure the wheels are within a certain % of one another. I think it would be a good idea to try and tap into this data feed if you can.
The Raspberry Pi is powered from the car, boots up with the ignition, gets GPS data and then will be able to display sat nav and/or current GPS derived speed on an integrated screen. You can customise the screen output using the NAVIT software.
Thank you for your reply. Certainly, if I only wanted to see the speed and engine RPM, it would be much simpler to create a setup like a racing car, embedding standalone, commercially available speedometers and tachometers into a carbon or other type of panel. However, I want to finish my car with a stock-like appearance, as if it were a model originally sold by the manufacturer. That’s why I would prefer to modify the original instrument cluster and proceed in that direction.
In fact, although I’m not sure how easily this can be found through searches from outside Japan, searching for terms like “L880K center tachometer” within Japan reveals a number of aftermarket modified clusters—sold by individuals or tuning shops—where the speedometer and tachometer have swapped positions. I’m aiming to build something like that myself.
Thank you for your reply. To be honest, I was a bit worried that people on forums like this might not think well of newcomers like me, so I’m relieved to have received such a kind response.
It’s true that the process of swapping the tachometer and speedometer itself is quite simple — it just involves cutting the circuit board and reconnecting the wiring. However, the problem is that unless I change the scale of the speedometer, it will only be able to display up to about 140 km/h, which is an issue.
Also, I don’t want to risk damaging the current meter, so I’m planning to modify a used one that I bought. For that reason, I also need to rewrite the odometer.
Maybe you could use the internals of a universal aftermarket speedometer inside the factory casing? The downside would be having to install a separate speed sensor