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Do you know how the resistance varies between full and empty? If you measure the resistance with an ohm meter, what do you see at those full and empty? You may need to use a different value pull-up resistor than what is built-in to get enough voltage swing to measure accurately.

The pull-up resistor makes a voltage divider with your sensor being a variable resistor. You can you can calculate the resulting voltage with this:

Volts = ReferenceVolts * R1 / (R1 + R2). ReferenceVolts is what you've connected the pull-up resistor to (typically 5V), R1 is the resistor between the signal and Ground (so your sensor), and R2 is the resistor between the signal the the Reference Voltage (the pull-up resistor).

Now, if your sensor measures close to 0 ohms, you have to be careful not to use too small of a pull-up resistor, as the overall current will be too high. A good minimum overall resistance is about probably 200 ohms (V=IR, so I=V/R or a max current of 25mA).

Thank you for the response David. I have checked the resistance for the sending unit and the numbers I have are as follows. Empty=110omhs Full=.9 ohms. I’m not sure If I’m doing your calculation correctly to find voltage. So This is what I came up with.

5(reference volts) * 110(r1) / (110+ 1000) = .495v

5 * .9 /( .9+1000)= .005v

Your math looks perfect. So is the pull-up resistor in the IC7 dash a 1000 ohm (1k?). Is the Reference Voltage 5V (or maybe even 3.3v if it's internal)?

So you could just enter the values of .495 full, and 0.01 empty (you may want to go a bit above that, 0.025 to have a " 5% reserve").

If you provided your own external pull-up resistor of say 402 ohms (that is a standard resistor available in 1%) to a 5V supply, then you would have a maximum voltage of 1.07 volts, and a minimum voltage of about 0.01v.

A resistor like that would cost 11 cents -- of course you'll pay more for shipping. Get a few for your friends!

Once again thank you so much. I’m gonna try that and see what happens

You are welcome. Happy to help.

I think you'll just have to study it to see what happens.

I’ll definitely keep an eye on it thanks for all your help David I really appreciate it