The solution is to change the roles of the tanks in the plane's configurator. at Weight & Balance Tanks on Xplane. issue solved.
Hi Vlad and community
After several attempts I started the fuel gauge, without problems Arduino Uno, I only found a problem with the selection of the main tank FUEL TANK 1 (MAIN) and the reserve tank FUEL TANK 3 (AUX) when operating the switch for the selection always shows the sum of the two tanks and not independently at their actual levels.
the pins (20) and (21) of the Arduino nano works erratically and cannot be adjusted. Please review them.
second question, how do I adjust the tank gauge FUEL TANK 3 (AUX) since in the configurator it does not appear for adjustment.?
When the MAIN-AUX switch is on, the stepper motor shows zero KGS (lb) with tanks full of fuel
For the Beech1900 secuence of fuel tanks
LEFT SIDE FUEL
TANK 1 MAIN (725 KG, 1603 LBS)
TANK 3 AUX (282 KS, 623 LBS)
RIGHT SIDE FUEL
TANK 2 MAIN (725 KG, 1603 LBS)
TANK 4 AUX (282 KS, 623 LBS)
As you can see there are two calibrations for each side of plane
Thank you for your help Vlad and the community.
this last photo shows that there are no changes in the main tank 1: https://i.ibb.co/Gt0yWNJ/Fuel-Sim-Vim.jpg
I am testing aircraft C90 and the fuel panel module works perfectly, this is what I want in the B1900 airplane, but it has been impossible for me community help me please.