ADU fuel level calibration set up help please!

ADU
1

Ok, I have already calibrated another vehicle and I have several more to do coming up and this one is another Toyota, a bit older than the first but Toyota nonetheless.

I have spent now many hours trying to get this calibration scale accurate and I am losing my mind now. I i can either get the gauge reading correct one way or another bot not empty to full sweep for a 40L tank.

I have measured the voltages in 5L increments, input the data into the calibration scale and then ran the test sweep again and its incorrect, again. The filter settings also don’t seem to do much so when the fuel moves, it drastically changes the levels, i am unsure if there is enough adjustment to help the filter.

The fuel sender is a factory 0-110 ohm Toyota one and I am using a 56k resistor with 5v out from the ADU.

Filling a tank every 5L then draining it again is not ideal and takes a lot of time.

Anyway, readings from my tests are:

5L increments
3L - 1.53v
5L - 1.88v
10L - 2.29v
15L - 2.67v
20L - 3.22v
25L - 3.66v
30L - 3.88v
35L - 4.08v

40L - 4.41v

So the issue that I am having is the voltage sweep seems to be pretty stable on my multimeter but the display doesn’t seem to correspond with the voltages i am seeing in relation to where the fuel level sits on the gauge or table, I have no idea what i am doing wrong, the instructions are pretty vague here with no problem solving suggestions etc.

with zero fuel in the tank, the adu thinks there is still 18L of fuel in the tank.

I have added a photo so you can hopefully see what i am talking about, can anyone help?

level calibration after test, I can only attach one photo sorry!

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2

zero fuel in tank but showing as half full (18L)

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3

Start by changing the pull-up resistor. 56kΩ is far too high for a 110Ω sender. Try a 100Ω resistor instead, this will significantly improve your voltage resolution. Also, take a look at this topic: Calibrating fuel level

4

56k resistor as pullup is defenitly bad, but i don’t understand how u could reach those voltage readings then….they look good and dont fit to 56k resistor.
How exactly did u wire it?….are u connecting the sensor to a sensor ground?

5

Thank you, I have changed to 100 ohm resistor on A5 and taken new readings of 5L increments, the net result is the same, still wont read below half tank, in fact now it reads no less than 33L out of 40L. The marker indicator inside the calibration window suggests its seeing a much different voltage than I am seeing at my multimeter and I am unable to find anywhere within the ADU that allows mw to see what Voltage it is seeing on A5 so i am relying on my multimeter.

This is frustrating, another 2 hours gone for myself and my employee.

I have gone over that link too and I can’t see anything we have done differently other than not having the channel set to ecu.fuel as it only operates when on a_Fuel Level as the fuel level is not wired through the ecu.

EDIT: it would seem we were looking at the wrong or different voltages that we could not see earlier, we have now found the ADU input voltage information to use to calibrate the fuel level and put it onto the set up page for ease of access and set up rather than using the multimeter. The whole fuel level set up system is pretty clunky and not exactly user friendly.

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6

Ok so for a test I have connected a 100 ohm resistor and repeated the calibration test, the voltages do change so i have input those into the software and the results are now worse.

ground is via chassis ground at the back of the car, however again for a test we changed to sensor ground and no change in voltage.

After some investigation, we have found our reading on our multimeter is somewhat different to that on or ADU display A5 pin which I did not see earlier, the way the screens are set up I was not aware you could see the input voltage so its completely thrown us.

We have completed the calibration process again using the ADU voltage readings and now the gauge works properly, we have found the sender also seems to be dodgy and has large fluctuations in voltage around 15L so we will replace. i have re positioned screens etc so we can see this information better at hand.