RV Repair: monitor panel, fifth wheel camper, grey water tank

Question
QUESTION: I own a 2003 fifth wheel camper. The fresh water tank monitor reads full all the time. What is the best way to trouble shoot this problem? Thanks

ANSWER: DICK
HAS IT ALWAYS READ FULL OR IS THIS A NEW EVENT?
WELL FIRST LOCATE THE TANK SO YOU CAN SEE WHAT TYPE OF LEVEL SENSORS ARE BEING USED. THEN LOOK AT YOUR MONITOR PANEL AND SEE IF THERE ARE CALIBRATION "POTS" ON THE BACK. IF SO YOU MIGHT BE ABLE TO ADJUST IT.
IF THE TANK USES WELL NUTS (EIGHT SCREW IN FITTINGS WITH WIRES ATTACHED)
YOU CAN TRY TAKING A SMALL JUMPER WIRE AND TOUCH IT TO THE BOTTOM LEFT ONE OF THE MIDDLE NUTS WHILE SOMEONE WATCHES THE PANEL FOR READINGS.
IF YOU GET READINGS, LET ME KNOW AND WE CAN GO FROM THERE.
SOME TANKS USE A FLOAT SYSTEM BUT FEW..MOST USE A WATER RESISTANCE SYSTEM THAT MEASURES THE ELECTRICAL CURRENT RESISTANCE TROUGH WATER.

THOM

---------- FOLLOW-UP ----------

QUESTION:
Thanks Thom, I bought the trailer new and the fresh water monitor worked ok then it started reading full all the time. I could only find 4 sensors with wires on them. I have not taken the monitor panel off,but it is a multi use panel with black and grey water tank monitors also. Hope this helps.
Dick

Answer
HI DICK
ARE THE SENSOR VERTICAL?
IT'S STARTING TO SOUND LIKE THE RESISTORS HAVE FAILED OR THE PANEL ITSELF HAS GIVEN UP.
WITH THE RIGHT EXPERIENCE ONE COULD REMOVE THE WIRES FROM THE SENSORS AND SHUNT THEM TOGETHER IN DIFFERENT PATTERNS TO SEE IF THE PANEL STILL READS A SIGNAL. THERE IS NO REAL VOLTAGE THERE SO YOU SHOULD BE FINE.
DON'T LET THE SMOKE OUT.

THOM