From the instructions:
***Manual Calibration***
How to calibrate the FUEL LEVEL gauge to a custom Ohm Range:
If the preset ranges will not work for your fuel level sender then you have the option to manually calibrate the gauge.
Required: Fuel level sensor MUST be connected to gauge during manual calibration. The Fuel Level sender must be in the corresponding Full or Empty state that you desire to calibrate. (If the fuel level sender is installed in a fuel tank, the tank will have to be full to calibrate the full condition and the tank will have to be empty to calibrate the empty condition.)
1. While the gauge is powered up, press and hold the button down for 10-12 seconds until pointer (needle) points at ‘1/8’ tank then
release the button.
2. Press and release button until the pointer is pointing at the 'F' (see figure 1). Hold the button down for 2 seconds. Release the button;
the pointer will now oscillate between 'E' and 'F'. You are now in Manual Calibration mode.
3. To calibrate Empty condition, follow manual calibration steps 1 & 2: While your fuel tank is empty; when the pointer points at ‘E’ press the button. The gauge will exit the calibration menu and will attempt to display the current fuel level.
To calibrate Full condition, follow manual calibration steps 1 & 2: While your fuel tank is full;
when the pointer points at ‘F’ press the button.
The gauge will exit the calibration menu and will attempt to display the current fuel level.
Important: Both Empty and Full conditions have to be calibrated before the gauge will display the fuel level accurately.
