Sensor Panel Help Please

[DKDarrow]

I have an 89 Excella that is close to being near perfect. The only problem that I cannot solve is the sensor panel in the range hood that indicates battery, grey, black, and fresh water levels. It reads the battery level just fine; but when checking the other levels the indicator reads empty no matter what the true level is. If you hold your tongue just right it will just for an instant scan full or perhaps even true.

I researched on here several months ago and a fella was trying to get a line on someone to repair this. The part is unobtainable from the factory, In Land Marine, other dealers, used parts, and other salvage places.

I took the panel off yesterday and it is manufactured by Larson Electronics Mfg, in Fullerton, Ca. Many hours of research found the company who bought them out back in the mid 90's. A tech there informed me that they had no way to repair them and the one guy who used to do this is now overseas.

The electronics is old style transistor, resistor, diodes, capacitors, etc.........Calling to find someone who could troubleshoot these old devices in the Atlanta area has found no one...........I find this really hard to believe. Even someone who could take the little board and directly replace the components without testing them.............

So, yes, I can look down into the tank of the black water from the toilet and judge from that when it needs to be dumped. The grey water, when it begins to back up into the shower needs taking care of. It's the fresh water that has me stumped as to get a reading on. I hate to drag around all of that weight or even worse not to be able to plan booney water replacement needs.

Yes, as the really nice parts lady at Inland suggested I can put a new sensor system in; but I just finished up redoing the bottom skin and really do hate pulling that, the tanks, etc to put in new probes................

What to do?............thanks guys...........Dennis

[ArtStream]

Hi Dennis and Sue!
Looks like you buttoned her up a little premature

It may be the Sensors and NOT the METER!

Sensors are notorious for failing, even the new systems.
Just like gambling folk, some people have the luck, others don't!

Your best bet would be a salvage yard. Most all RV's and trailers used this brand meter/sensor, so it's a good bet that there are a ton floating around out there.

Your tank sensors actually working is another issue

RV Salvage yards

Let us know the outcome.

Best,
Michael

[clancy_boy]

There are re-calibration techniques that you can try so that you can localize it to the sensor or maybe cure your problem. If you do not have the manual - try contacting the manufacturer or search here for other posters who have had this issue. I had read one thread that had the manual in PDF file format scaned in. I will look for it or someone else may know where it is.


Good Luck

[ArtStream]

Hi Clancy_Boy!

In 1989 it was WYSIWYG.

There were no calibrations, like on your late model unit.

M

[clancy_boy]

Originally Posted by ArtStream

Hi Clancy_Boy!

In 1989 it was WYSIWYG.

There were no calibrations, like on your late model unit.

M

ooopppps - sorry about the bad info, I had to do mine on the 03 CCD when I got here. That's what I was thinking about. Thank You ArtStream.

[DKDarrow]

Actually, I believe there is a way to calibrate them, if mine was working I could tell you. Went back down to the trailer to look at the panel. Each button you push to check the various levels is a rheostat/switch with an adjustment screw on the back. Put a drop of WD-40 on each screw and then screwed them in and out to the stops a few times.............NOTHING......

Pulled the terminal plug off of the end and cleaned the contacts........NOTHING.............

On Monday, I will start calling the salvage places that were posted..........
Thanks Guys.......I keep trying..........God Bless........Dennis

[Motoman]

If you think the switches in the panel are intermittent, i.e. you indicated the panels sometimes indicates, you might get some electronics spray cleaner and spray it in the switches as you work them back and forth. Make sure you buy a cleaner that is made for plastic so it doesn't damage the panel or knobs. Re-calibration of any pot or rheostat may be necessary afterwards.

You can try a Radio Shack but most seem to be just cell phone shops now days, An industrial electronics supplier like Electronics Warehouse would be a good place to look and they might offer some help in selecting a spray electronics cleaner.

[DKDarrow]

Motorman............Looked and checked and checked yesterday about if the switches are actually intermitent..........THEY ARE NOT..............They just flash all the way across the board as you work the switch in and out........

I used WD40 on the back of the switch; but just a drop......I like your idea about the electronic cleaner. This will allow me to "saturate" the assembly.......

Any ideas about how to check or get a reading on the fresh water level?

Dennis

[BillTex]

Hi Dennis, it was me you spoke with a few months ago. My board has the EXACT same symptoms.
Here is what I found out so far;

• You are right about Larson, I went through the same exercise. Spent considerable time tracking them down...no luck in replacement/repair.
• I did speak with an electronics troubleshooting company. When I first approached them last year,they were willing to troubleshoot/rebuild the board for maybe ~$200. I called them back (with you in mind as you said you were interested) and they have changed their tune. Sounds like they have taken on some bigger customers and were not as interested in fixing our boards. They would do it, but wanted to get some minimum amount of boards to make it worthwhile (I don't blame them).
• I tracked down an identical board (finally) from another member (who had a tree total their AS) they said their system was working fine. I received the board, plugged it in and ???gues what, same symptoms....so...sounds like the problem is elsewhere (which is good news, I think).
• BTW, I called DOZENS of salvage yards, even had some other members visit salvage yards around the country and could not find a single one of these boards...so good luck trying to find one.

So what's next? As I believe the problem lies in the wiring harness, some where between the board and the tanks, I will get under there AGAIN and look some more. I am convinced it is NOT the board. The weather has been too crappy here to crawl around underneath and troubleshoot this. I hope to get to it this week. I believe it is a commen ground that is the problem, as you have found, battery level is fine, light, fan, etc all work. It is just all 3 tank indicators that quit working. I will post details of what I find and how I fix it soon.
One more option; a simple meter (Radio Shack-mounted inside cabinet?) to monitor fresh water level. As you have noted, I can get around the gray/ black tank levels. Fresh water is critical....

Stay tuned, Bill

[Poprivet]

Check the common ground at the sensor panel. I think a high resistance in the ground would cause the problem you describe.

[DKDarrow]

Hey Bill........and MR. Pop Rivet.............Good to hear from you Bill!!!!

Hmmmm this sounds encouraging about the common ground. Wonder where that might be???..........In the panel wiring???.....You are correct about the battery itself getting readings and lights, fan, etc working, so that would mean that the ground is good there......So would the ground for the sensors be between the panel and the tanks...........???????
The plug on the panel board has bare wires on it would seem each sensor circuit/tank......I assume these are grounds for that particular tank/sensor.......
I need to pull the panel off again and see if I can trace that particular harness/bare ground wires as they leave the panel/board plug......

Getting ready to head out in the trailer for a few days/week or two.....SO PLEASE LET ME KNOW WHAT YOU FIND.......I will be monitoring this..........

THANKS............Dennis

[DKDarrow]

Susan is packing groceries away in the trailer as I write this so I can't get to removing the panel.........What I will do in a moment or later is:

The plug that attaches to the panel/board is one of those multi plug/wire connectors.........a flat plug with perhaps 12 or so different sockets that slides onto the board connectors........The wiring from the various sensors plugs into the board here.......There are several bare wires, with NO insulation at all on them going into this plug as they come out of the wiring harness..........I plan to use an ohm meter to one of these bare wires to see if there is actually a ground from where ever it is they come from.........If I touch one of these wires with a probe of the ohm meter and then to a common ground, like the light or something else that is there and DO NOT get a reading then that should tell us if the ground theory is correct..........

Then it would be a matter of following that wiring harness back to where it goes to pick up it's ground................

Thanks for the help........will let you know..........Dennis

[DKDarrow]

Well shucks...........just tested what would seem to be the ground wire for each circuit and they ALL test out as a closed circuit...........A probe of the ohm meter on the gound wire and then over to the ground wire of the water pump..............Continuity on each...........

I am dyslexic, see things backwards sometimes, especially circuits.......Please bear with me........Put the probe on the ground wire and on the other wire of the sensor and got a closed/circuit.........shouldnt I be getting an open, no reading on the ohm meter........that is until the button/swtich is pushed which closes the circuit?????

And no......I still do NOT believe it is the sensors themselves because for all 3 of them to fail defies coincedence..................thoughts?????

[DKDarrow]

Bill..........what kind of meter are you refering to about the fresh water level......would it use the existing sensors?????

[BillTex]

Dennis, if I understand system correctly, your tank (s) would need to be full to return a voltage.
Fill up your fresh and see what you get.

Yes, any gauge/meter that reads within the same voltage (12v) as the camper should work. I had the exact voltage returned from the sensors at one point but can't remember now (CRS disease) but I believe it was in the owners manual. I was planning on using the stock sensorsIF the panel was garbage. Now that I am fairly convinced it is NOT the panel I am going to invest more time doing what you are doing at this moment; tracing back all the gorunds (it MUST be a common ground) and finding the bugger.

Like you, all 3 of my tanks quit at once. Worked one week, next week they were blotto...

Let me know what you find, I won't get to it until later this week.

Bill

[richinny]

you might try looking for on old tv technician or advanced ham radio type. they might have the know how to check out some of the board components. i once knew someone that could repair almost anything on a board.

i agree that for all of them to fail at once seems to indicate something all those guages have in common. a bad power source connection might feed a bit of voltage until the current draw forces the circuit to fail as with a bad connection at a splice or fuse.

happy hunting!

[Tarheel]

I have never seen a board that worked properly. It is my humble opinion that the purpose of the lights is to look pretty and impressive to someone that doesn't know any better. they didn't work properly on my 94 nor do they work properly on my 2001. They are not horribly off but I know as much from how long I have been out as to the status of my tanks, battery, and propane as the indicator lights tell me.

[DKDarrow]

Thanks Guys...........Does anyone have an idea as to exactly where the sensor panel/tank sensors actually pick up their power?............Must be at the fuse panel at the power supply????????

[strmstr69]

Be sure to check the solder joints around the plug on the board. These areas can break loose and cause a bad connection. Resolder them and maybe this will help.

[BillTex]

Well I have checked everything I could find/see. Even tried the other board from salvaged AS that PO said was working fine.
Symptoms are the same with both boards, so it MUST be in the harness?

Catastrophic/sudden failure or all 3 tanks at once, and ONLY the tank gauges (battery/lights/etc work fine) all 3 tanks read "E" only.

What connection do all 3 tank sensors have in common?

Any ideas?

Thanx, Bill