Welcome to SCoA! All I know is when there are no bars left on the fuel gauge you need to fill up....
Fuel level voltage showing was 2.74 volts and the fuel level display was at 1/2 tank, or 4 of 8 bars. Most vehicle 5 volt sensors use a input operating range of 1/2 to 4-1/2 volts so as to differentiate between a valid input and one that is shorted or open. Many systems use a floating or isolated sensor return or ground slightly above chassis ground for electrical noise isolation.Rustedwrench,
You have contributed with a superb key piece of information..! If I can get the sensor voltage, that's all I need.
Yes, I have some schematics of the electric system and I have been aware of that flow you described from the M3/3 sensor on the fuel tank to the A1 cluster. What I haven't figured out until now is that what really moves through the CAN bus to the cluster is not the final fuel level information, but just the output voltage of the M3/3. That changes the whole scenario, things start making sense again.
Now that I know what is the right information to look for, I'm going to check again my sample files, captured few days ago at different fuel levels, to see if I can pick up something. If not, sniffing between the car and a scanner (particularly one of those you have mentioned) to look for a propietary query will be also a good second choice.
Thank you so much for your time making the tests and pictures on your car, and also for such a valuable comments.
Will keep you updated with fresh results.
I suspect that is the case but I never had any reason to look. You could monitor the actual voltage at the DME connector pins to verify it. Pins 68 and 62, PNK and BRN/PNK. The DME is behind the right side interior panel in the cargo area, just ahead of where the access panel for the right rear lights is located. Click on the attachment to magnify it.Rustedwrench,
Just by chance, have you noticed if the voltage/fuel-level relation is inversely proportional? If so, I guess (probably, hopefully) I got something...