- Location
- Melbourne
- First Name
- Ed
- Drive
- 2000 Legnum VR4 Manual, Ford Territory family runabout, BMW K1300R.
EDIT: This project is now complete and successul, however I recommend skipping to the posts from 2021 as most of the stuff in between is hot garbage because I had no idea what I was doing.
So folks, the Legnum fuel gauge non-linearity shits me and I want to fix it.
My plan is to put together an Arduino-based solution that does the following:
The only problem with the job is that to calibrate the gauge I'll need to drain the tank to empty and then fill the tank an exact consistent amount (say, 5 or 10 litres) at a time, measuring the resistance of the fuel sender and needle position at each interval. I keep doing this until the tank has 60 litres in it. From here I build my table of original values and the needle position, and can use it to extrapolate a desired needle position for each amount of fuel consumed.
The goal will be for the needle to read as follows:
It's funny but one of the guys I work wrote the code for the Magna and 380 dashboards when he worked for Siemens VDO. He'd probably have a good idea about the code within the dash itself. Might help!
So folks, the Legnum fuel gauge non-linearity shits me and I want to fix it.
My plan is to put together an Arduino-based solution that does the following:
- Disconnects the gauge from the senders
- Sends a 5v signal to the fuel senders and measures their signal using a voltage divider with a 1kohm resistor
- Connects the gauge to a digital potentiometer whose resistance is controlled by my calibrated resistances that will make the needle point where I want it to
The only problem with the job is that to calibrate the gauge I'll need to drain the tank to empty and then fill the tank an exact consistent amount (say, 5 or 10 litres) at a time, measuring the resistance of the fuel sender and needle position at each interval. I keep doing this until the tank has 60 litres in it. From here I build my table of original values and the needle position, and can use it to extrapolate a desired needle position for each amount of fuel consumed.
The goal will be for the needle to read as follows:
- Full tank: F (duh)
- 45 litres left: 3/4 mark
- 30 litres left: 1/2 mark
- 15 litres left: 1/4 mark
- 10 litres left: Fuel warning light comes on (whatever needle position this needs to be)
It's funny but one of the guys I work wrote the code for the Magna and 380 dashboards when he worked for Siemens VDO. He'd probably have a good idea about the code within the dash itself. Might help!