Technical Voltage and water-gauge not working

[FreeCamper]

This little instrument is bugging me... It is meant to show battery-voltage and water-levels, but the only thing that happens when I press the switches, is that the backlight comes on. Tips will be highly appreciated.

 

[Communicator]

As presumably the meter fails to respond to any of three inputs (battery voltage, fresh water, and waste water) the connections to the meter, or the meter itself, may be faulty. A digital multimeter connected in parallel could be used to confirm that voltage is present at the meter terminals.

 

[FreeCamper]

Thanks. I will try...