Black Water Tank Sensor Never Changes

[trwestman]

I replaced an old black water tank sensor and still have the same problem. Low light is on always regardless of level. I never shows any other light.
Any suggestions on electrical diagnosis steps.

[g36]

You should be able to short the different pair wires to illuminate the other lights on it to rule out bad wiring or indicator lights.

[paulr]

My 2001 Carver 396 had the same problem.
The factory installed TankWatch® 4 Water/Holding Tank Monitor system completely failed last year. The tank sensor has 3 non serviceable reed switches inside the dip tubes that are used to complete the circuit to 3 different level lights on the monitor. After removing and testing the sensors from the tank, 2 of the 3 switches were bad.
I removed the monitor from the cabinet in the head and bench tested it and found non functional as well.
I replaced both units and now the system works perfectly giving me peace of mind.
The job took about 4 hours and over$400 in parts.

[Midnightsun]

May want to take a peek at this link where I ended up scrapping the original Carver unit and going with a Blue Sea unit in the end. Has been flawless. viewtopic.php?f=7&t=6393&p=61028&hilit=oled+blue#p61028

[trwestman]

Yes I tested the unit and compared readouts from Volt-Ohm meter. Sure enough the display was bad. Found a new replacement on eBay. Shipping from England. Thanks for all the responses.