How to display Voltages using SPDT Switch?

Hi ...
I am using arduino with joystick to control the motors wirelessly with Single Pole double throw switch.

Here is the schematic.

With Single Pole Double Throw Switch, I have the voltages shown with the switch slide to the COMPUTER side using RS232 and OLED. I want to see the voltages to the JOYSTICK side, how can I see this and which wire do I need to short or any other thing to implement ? I will be very thankful to you ...

@mubashirazmat you posted this in the installation and troubleshooting section. This section is just for getting the system working it is NOT FOR YOUR PROJECT.

Therefore I have moved it to a more appropriate section.