Black tank sensor always reads at least 1/3 full

[Herk7769]

Horst Miracle Probes for Wastewater Tanks in Recreational Vehicles RVs

Be sure to watch the "How It Works" video and the "Install video.

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[RV Wizerd]

There should be four sensors on the tank one is ground and the other three to the level indicators. You only need to fill about 1/3 full then as I said before take the trailer for a ride and let the agitation do its work, another thing is how old is your rig as the probe might need replacing as it could be defective or there might be a short somewhere in the system wiring, to do a test disconnect the ground probe wire and if the indicator goes out the tank has solids still if it doesn't go out then there's a short in the wiring.

[Herk7769]

As you can see, the 1/3 full light (when working perfectly) will come on with one good flush (or any residual sludge that is not turbo-flushed out).

The 2/3 light comes on about 1/2 tank and the "FULL" light will come on at about 3/4 to 7/8 of a tank.

OEM Sensors don't "go bad," they just get dirty.

Take a minute and watch the Horst video.

[Joe A.]

Lou, what are the red and white wires under the black patch on the bottom of the tank. I replace 4 sensor in my grey tank and all 4 are still on. I'm going to do you test over the weekend.

Joe A.

[Herk7769]

http://www.forestriverforums.com/for...tor-26746.html

I am just about ready to replace mine, but I decided to do my annual winterizing tank prep on my gray tank first.

The problem is this:

ANY probe that satisfies the following condition will turn on lights. For example the TOP "FULL" probe can actually be the one turning on the 1/3 light.

Here is how you can tell which one is "dirty":

First make sure the tank is empty, then:

1) remove all 3 wires on the indicators and put tape on them; but leave the RED (signal to panel) wire AND the WHITE (ground) wire alone.

2) Press the Gray tank button and the reading should be EMPTY. If not you will need to replace the circuit board in the monitor.

3) Touch the Yellow wire directly to the Ground Probe (white wire) and take a reading. It should read 1/3 full. Remove and retape the Yellow wire.

4) Touch the Green wire directly to the Ground Probe (white wire) and take a reading. It should read 2/3 full. Remove and retape the Green wire.

5) Touch the Orange wire directly to the Ground Probe (white wire) and take a reading. It should read "Full". Remove and retape the Orange wire.

If all that works the monitoring system is working fine and the trouble is dirty probes in the tank.

The way the lights work:

If there is no liquid in the tank AND there is no path (slime etc) to the ground probe from any probe that has the following resistance between ANY level probe and the ground probe will turn on the appropriate light.

EXAMPLE:
ANY probe meeting these criteria will:

Infinite resistance (open circuit - empty tank) -> EMPTY light on.
188K ohms or LESS (high resistance path to ground probe) -> 1/3 light ON
68K ohms or LESS (LOW resistance path to ground) -> 2/3 light ON
40K ohms or LESS (VERY low resistance or SHORT to ground) -> FULL ON

So how to clean the probes: I tried ZEP Purple Degreaser; but it did not work well. My FULL light went out; but the 2/3 light stayed on.

NOW I am using the RV-Digest-It Winterizing method of tank cleaning to remove hair, kitchen grease, and soap scum. It is out there cooking right now and I will report in 48 more hours.

Changing the probes may not fix this problem if the tank walls are really slim'ed. I have a lot riding on this treatment because trying to scrub the walls of the gray tank with a small bottle brush and degreaser is going to suck

[Herk7769]

Originally Posted by Joe A.

Lou, what are the red and white wires under the black patch on the bottom of the tank. I replace 4 sensor in my grey tank and all 4 are still on. I'm going to do you test over the weekend.

Joe A.

Joe, the red and white wires go to my tank heaters.
UltraHeat - UltraHeat Webstore

[Krazymace]

On my 6th RV. Black tank sensor hasn't been consistently accurate on any of them. Really hasn't been a problem. Just empty periodically.


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