Tank sensors

[Ray Lenning]

Think I have the answer but want other suggestions . My black tank always shows full on my 2005 National Dolphin 5355 even when I remove all four sensor wires from the tank or unplug the coupling going to the sensor wires were it connected the tank . So , I think either there is a short some were between the common and the sender wire back to the display panel for the black tank or maybe that part of the display circuit board is bad . Fresh and gray tank both work correctly . Any suggestions greatly appreciated .

[450Donn]

Ignore the sensor readings. Learn to dump the tanks when their full.

[Ray Lenning]

Thats what we do , it's no big deal I just like to tinker and was looking for some input on what I may be missing .

[Vaflatlander]

I don't know for certain whether with an open you would have a full tank registered or whether a short would cause a full tank registered.try disconnecting the wires on the tank, first the top one, work your way down see if the light goes out or down. Good luck

[Kickman921]

Hi Ray, I also have a 2005 Dolphin LX 5355. I also have the same problems and I generally know when I should dump. I would like the sensors to work, but I don't know how to access the sensors on the black tank. How did you access them? What panels do I remove or what process to location them?

I want to troubleshoot them.
Thanks
Dan

[Ray Lenning]

Hi Dan , The black tank sensors are in the storage compartment just behind the rear tire on the passenger side . Look at the top right of the compartment to find a plastic cover . Remove the screws around the upper , lower and back edge to remove the cover . There will be for expanding foam in the front you will have to break loose . The Gray tank is in the compartment just ahead of the rear tires same side . The fish water tank is in the rear compartment on the drivers side . The also have the plastic cover over them . Be careful with the gray and fresh covers , they must be bent to get them off and on due to going all the way across the compartment . The screws in the gray and fresh tanks are in the top and bottom flanges .

Hope this helps .
Ray .

[Kickman921]

Very helpful! Thanks

[Glamping2]

We have had several motor homes over the years and usually the problems in sticking paper but this one in my 2006 5355 Dolphin. Is like yours stuck forever on full. I have treated cleaned and even pressure washed the interior of tank. All the others in the past I have been able to fix with these methods. I’m wondering after seeing what others are saying if there is an endemic problem with this model with the board or wiring etc. . We manage without ours but It would have been nice to have it working.

[FLRosebud]

I have pretty much the same issue with my 2006 SeaBreeze LX. The only time the black tank lights have worked correctly is after I filled the tank with water, dumped about 20 pounds of ice cubes in the tank, drove it around for 10 minutes, then dumped. Showed empty. Within a month it was back to showing 2/3 full after I dumped. So I pretty much ignore it now and dump when I know I have to.

Al

[Ray Lenning]

So after a bit more trouble shooting I have determined the problem is the circuit board for the tank sensors . I have ordered the board and a tank harness from JRV Products , a little over $70 for both . Should get it in about a week . I will post the results after I install it
P.S. I ordered the tank harness just to in case and it was only $10 so I have it if needed , if not I have a spare .

[C1v1leng]

Is the circuit board in the tank level display or somewhere else?

I know they are not accurate but I hate it when things don't work right!

After draining all my tanks including fresh water it shows full or nearly full. LP level is correct though.

Please post if this resolves your problem

[Ray Lenning]

The circuit board is located at the control panel were you check the tank level , it had the level indicating lights integrated to it. Two small screws and one coupling and its out. I should receive mine next week , I will post the results

[Ray Lenning]

OK I can say the circuit board did the trick , The black tank now shows correct level along with the other tanks.
Thanks to JRV Products for having the board in stock. The board was $53.70 .
Hope this may help some one else .

[Kickman921]

Thanks! I am going to order one. I have tried everything else.