Definitely looks like the same panel as on our 2014 model. The full manual is attached. If you have a volt meter with narrow enough probes you may be able to measure the voltage on the pins when the connector is plugged in. The water sensors aren’t powered up all the time, only for about one second every twenty, or more if the display is actively showing that tank’s reading. If you’re able to read the voltage on pin 3 you should see it spike to a voltage corresponding to the tank level (1-6 volts or so). If not then there’s a bad connection between the pin and the tank somewhere.