Swift Autocruise Alto 2013 Grey Tank Sensor Fault

I have a 2013 Swift Autocruise Alto (Peugeot Boxer).

The tank full warning is no longer working on the grey water tank.

The sensors are tip switch type. I have disconnected the sensor and put a meter on it. It is working perfectly. I have checked the wiring under the vehicle, and the connections between the sensor and the wiring loom and they are in good conditions.

The warning led on the panel is working as all the leds come on when it is turned on.

So this suggests a break in the wiring loom somewhere inside the vehicle. We have had mice in the vehicle (now eliminated) so I am guessing a cable could have been chewed.

It looks like the wiring runs between the floor in the van and the steel base, so is going to be virtually impossible to get at. So I am thinking one solution would be to identify the cable concerned at some point nearer the control panel, and run a new cable down to the sensor.

So, by any chance, does anyone have more detailed wiring diagrams for this model that might help identify the cables? The documentation I have found on the internet is not detailed enough.

I have two more solutions to this problem.

One is just to live without it, as I generally know when the tank will be near to full.

The second is to wire my own warning light and/or buzzer onto the sensor as that is still working.

Thanks for any advice or suggestions.