Systems monitor panel

I filled my water tank today and found a problem with the monitor panel. All the lights stay lit regardless how full the tank is. I checked the connections and all were tight. Shouldn't they either go out or come on as the water level changes?

[Bill]

Yes, they should change with the water level - all lights on when the tank is full, fewer lights as the tank empties. The sensor-and-indicator mechanism is pretty simple - no moving parts - so I'm not sure what the problem could be other than outright failure of the sensor circuit behind the panel. Is your TM new (can't tell from your tag line)? If so, call your dealer - it might be as simple as popping in a new circuit board.

You're sure you weren't looking at the indicator for the gray water tank, (or the battery), which works the same way...

Bill

Yep it's the water tank. The gray tank shows one light and the battery shows C when pluged in and G when unpluged. I called the dealer and he wasn't sure-said it sounded like a ground prob. He is 2 1/2 hrs. away so not worth going for just this prob. I can always look under the sink and see how much is in the tank. May call TM today. Should there be voltage on the sensors or just resistance? How much? Thanks

[Bill]

If the lights stayed off, I would agree with your dealer. But since they stay on, I'm not sure. Still could be a ground problem, I guess, but it would be on the monitor panel, not the tank sensors. And I'm not sure how that would happen, given the fact that the lights do, in fact, light.

If you look at the side of the tank, you will see three bolts with wires attached to them. On mine, the wires are yellow, green, and red. There is a fourth bolt farther back, which I can't see as well - I think the wire is white. The first three bolts are the "sensors", and the fourth is the ground. Yes, these "sensors" are nothing but bolts with the heads inside the tank. When the water wets them, it provides a conductive path from one or more of the three "sensor" bolts to the ground bolt.

The voltage that you can measure on these sensors depends on the kind of voltmeter you have. My cheapie analog meter just barely registers. My digital meter says there is 6.5-7 volts. This is measured with the tank empty - it might be different with water in the tank. And of course the voltage is present only when you push the test switch. Do you have a digital meter? If so, what do you measure? By the way, is this a new problem? Did it ever work right?

Bill

Ok maybe I stated things wrong. The panel has never worked. It only lights when the test button is pushed. My digital meter should read the volts on the bolts. When the test is not pushed there is no voltage. I'll need someone to push the button while I check. I am not sure where the power to the panel comes from if the button is not pushed. There are 4 wires that go to the board. 1 hot when button pushed 1 ground and 2 others that I can't tell where they go yet. There is a white ground that goes to the tank and a yellow that ties with the other sensor wires. I need to try and trace these wires and see where they go.

[RockyMtnRay]

[quote author=live2shopnc link=board=1;threadid=1886;start=msg13373#msg13373 date=1083285158]
Ok maybe I stated things wrong. The panel has never worked. It only lights when the test button is pushed. My digital meter should read the volts on the bolts. When the test is not pushed there is no voltage. I'll need someone to push the button while I check. I am not sure where the power to the panel comes from if the button is not pushed. There are 4 wires that go to the board. 1 hot when button pushed 1 ground and 2 others that I can't tell where they go yet. There is a white ground that goes to the tank and a yellow that ties with the other sensor wires. I need to try and trace these wires and see where they go.
[/quote]

Your panel is working correctly with regard to the lights coming on only when the test button is pushed..they should not be on otherwise. The reason is that if you are operating only on the battery (no electrical hookup), constant illumination of the panel lights (and associated measurement voltages/currents) would be a significant parasitic drain on the battery which in turn would greatly shorten the time before it was exhausted. Those of us who boondock (dry) camp at campgrounds that don't have hookups (e.g. Forest Service campgrounds) are very grateful that the panel lamps only illuminate when the test button is pushed.

Thanks Ray. Now; any idea why all the lights for the water tank come on when I push the test button regardless of how much water is in the tank?

[RockyMtnRay]

[quote author=live2shopnc link=board=1;threadid=1886;start=msg13379#msg13379 date=1083319635]
Thanks Ray. Now; any idea why all the lights for the water tank come on when I push the test button regardless of how much water is in the tank?
[/quote]

As Bill noted above, the tank sensor system is based on the difference in resistance between air and tap water (fresh water tank) or drainage water (grey water tank). It's is measured by applying a voltage to the the 3 upper sensors (bolts) on each tank and detecting through which (if any) of the sensors a slight current flows. If current flows through a given sensor to the ground in the tank via the water in the tank, the electronics in the panel illuminate the appropriate lamp. Since your lights do illuminate and an equal voltage is applied to all of the tank sensors on each test button push, measuring the voltage at the sensors is not only difficult but won't tell you much (if the lights failed to illuminate with a full tank, then checking for voltage at the sensors would definitely be called for).

Since all lights illuminate regardless of fresh water level, there could be several possible causes. NOTE: BE SURE TO DO THE FOLLOWING TESTS WITH THE TANK EMPTY OR NEARLY SO.

1. All the wires from the sensors were attached to the same terminal on the panel. This would be a dumb human assembly mistake and therefore possible on a new trailer. To verify this, first remove power from the trailer by disconnecting the negative battery terminal (and ensuring the shore power cable is unplugged). Now remove the test panel and inspect the wiring on the back. If all the wires coming to the panel are attached to different terminals, go to step 2. If they're on the same terminal, you'll have to do some troubleshooting to ascertain which wire should go onto which terminal. Note: I haven't removed my panel so the above is somewhat hypothetical...and I can't tell you exactly how it's done but I bet a peek under the sink would be helpful.

2. If Step 1 reveals all wires seem to be properly connected to the panel, you'll need to power up the trailer and then disconnect (from the panel) just one of the wires going to the fresh water tank sensors (should be fairly straightforward using color coding). Now press the test button:

a. If all the lights still illuminate, then I would conclude you've got an internally shorted panel and you should get a new one from your dealer or TrailManor.

b. If one lamp (hopefully the appropriate one) no longer illuminates, you've got something weird going on in the wiring to the sensors or within the tank itself. To check this, reconnect the unconnected sensor wire to the panel, then go to the tank and disconnect that wire (or another if it's easier). Again press the test button:

(1). If all lights are again illuminated, you've got a short somewhere in the wiring to the tank.

(2) If the appropriate light is no longer illuminated, then something's amiss at the tank that's causing current to flow along the internal tank wall even without water being present. Remove all sensor wires and use an ohmmeter to measure tank resistance between the sensor terminal(s) and the ground terminal. You may need to remove the tank to inspect it for some kind of internal problem.

Of all the above, causes my strong hunch is Number 1 (incorrect assembly of the wires to the panel) or Number 2 (an internally shorted panel).

Try the above tests in the sequence listed and let us know what you find...you should be able to do most, if not all, of these tests without having to have a helper.

OK: I have already removed the panel. There are 4 wires that go to the board. 1 red and 1 white that carry 12v to the board when the test button is pushed. Can't remember the colors of the other 2 but they seem to go into a bundle of other wires. I will have to cut the wire ties to trace them. There are 4 wires that tie together in a sealed connector. 3 of these come from the sensors on the tank and the other (red wire) ties to a yellow that goes behind the water tank somewhere with the white ground from the tank. I have been heading up a search/rescue mission for the last 3 days and have had no time to trace the wires It's back out on the water again today.
Thanks for the help
Ed

[RockyMtnRay]

[quote author=live2shopnc link=board=1;threadid=1886;start=msg13390#msg13390 date=1083417120]
OK: I have already removed the panel. There are 4 wires that go to the board. 1 red and 1 white that carry 12v to the board when the test button is pushed. Can't remember the colors of the other 2 but they seem to go into a bundle of other wires. I will have to cut the wire ties to trace them. There are 4 wires that tie together in a sealed connector. 3 of these come from the sensors on the tank and the other (red wire) ties to a yellow that goes behind the water tank somewhere with the white ground from the tank. I have been heading up a search/rescue mission for the last 3 days and have had no time to trace the wires It's back out on the water again today.
Thanks for the help
Ed
[/quote]
I wish you good fortune with the SAR and admire your public service in being not only a SAR participant but having the responsibilities of leading one. As the youngun's say: Awesome!

You'll still probably want to do some tests with detaching one or more wires from the sensors on the tank but given that everything's bundled up into one connector on the back of the panel, my bet is the cause is a defect in the panel's electronics.