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Old 10-05-2020, 05:34 PM   #1
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Question LPG guage and control panel don't match

I have a 2017 thor Chateau. The control panel in the cabin above the door shows the propane tank is full yet the guage on the tanks shows 5/8 full. Wires to the guage are all intact. How do you trouble shoot this issue and if turns out to be the sending unit on the tank guage, can it be replaced without removing the guage.
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Old 10-05-2020, 11:24 PM   #2
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"Full" is not actually full.
I think that you can only fill them to 80% of capacity. The gauge on the tank might be reading what's in the tank relative to what it could theoretically hold, and the panel. Is reading what's in it relative to what you can actually put in it
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Old 10-06-2020, 12:08 AM   #3
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Originally Posted by El Pirate View Post
I have a 2017 thor Chateau. The control panel in the cabin above the door shows the propane tank is full yet the guage on the tanks shows 5/8 full. Wires to the guage are all intact. How do you trouble shoot this issue and if turns out to be the sending unit on the tank guage, can it be replaced without removing the guage.
Rotate the sending unit on the gauge to calibrate it:

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Old 10-06-2020, 02:18 AM   #4
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LPG guage and control panel don't match

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Rotate the sending unit on the gauge to calibrate it:







Say what? I'm seriously confused....

The gauge / sending unit just snaps on to the tank. There is no adjustment that I'm aware as it is reading the float level in the tank. I believe it is magnetic.

The gauge will read out the level based on the float in the tank and then send that signal inside the coach for a digital remote readout.
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Old 10-06-2020, 03:08 AM   #5
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My understanding is that you can rotate it to change the reading in the coach.
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Old 10-06-2020, 10:13 AM   #6
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I had to research that one.......

On my tank it could be installed in one of four positions.... where the Full indicator is at 3 o'clock, 6, 9 or 12. That means a potential of a 25% error if not positioned properly.

I found this video that explains how the tank level and manual gauge vs electronic gauge works.




Based on this video, I'm going to assume that for a horizontal tank should have the gauge / sending unit where it is readable such that the Full indicator is 3 o'clock.

From what I found reading more about the sender is that it works based on resistance. Most of the horizontal tanks used in RV's require a sending unit that is based on a 0 to 90 Ohm reading. As the float inside the tank moves the resistance changes and that results the level reading inside the coach.

So if the readout is no matching the actual amount of propane in the tank it would either be a problem with the float or a bad sending unit.

The sender on my tank is this one.....

https://www.amazon.com/Manchester-Ta...09373264&psc=1


So after all that..... I'm not sure there is an adjustment for the sending unit.
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Old 10-06-2020, 12:30 PM   #7
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Nice video Judge. I always wondered how those gauges worked. My inside gauge on my control panel and the gauge on the tank itself always agree, but I wonder how accurate they actually are. Anyone have any thoughts on that?
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Old 10-06-2020, 01:16 PM   #8
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LPG guage and control panel don't match

Iím guessing there is a variance between actual and reported levels of 10 - 20% given itís magnetic and not a direct connection between the float and the gauge.

You have to think that the level of the coach will have some effect on the reading since it is the liquid moving the float.
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Old 10-06-2020, 01:57 PM   #9
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All, I'm not sure how to troubleshoot the issue. I don't know if its the sender that isn't changing resistance or the control panel not reading the resistance. One day it was working the next not. I guess I could cut the wires and read the resistance of the sender by using an ohmmeter. Assuming the resistance is linear 1/2 full would be 45 ohms etc. If the sender is changing resistance then it must be the control panel circuit that's faulty.

Any other thoughts?
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Old 10-06-2020, 02:40 PM   #10
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Iím usually a pretty anal sort of a fellow, but speaking for myself I wouldnít worry about it. Coach panel gauges are notoriously inaccurate as are cheap gauges like they put on tanks. I fill up my tank when both are showing that itís getting low. Then knowing how much it took to fill it up and what he capacity of the tank is I can judge accuracy for the next time. It thatís just me.
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Old 10-06-2020, 03:02 PM   #11
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Originally Posted by El Pirate View Post
All, I'm not sure how to troubleshoot the issue. I don't know if its the sender that isn't changing resistance or the control panel not reading the resistance. One day it was working the next not. I guess I could cut the wires and read the resistance of the sender by using an ohmmeter. Assuming the resistance is linear 1/2 full would be 45 ohms etc. If the sender is changing resistance then it must be the control panel circuit that's faulty.

Any other thoughts?

The only thing I can think of is to go to a Propane Distributor who specializes in tanks, etc. They may have a way to test that the float and sender are working properly.

The sending unit is about $50 so a bit expensive to buy one to try if it is not the problem.
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Old 10-06-2020, 04:31 PM   #12
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So I decided to do a little experiment..... to prove the magnetic float and sender unit do actually work the way they should. Maybe this will also help the OP and others troubleshoot an issue with the propane tank readings.

I took my sender, which was reading about 1/2 on the gauge and about 60% on my Firefly display and rotated it about 45 degrees.

As you can see from the pictures it went to about 3/4 full, which is what I would have expected given its magnetic. My Firefly display read 100%. I wasn’t too surprised because I noticed it read full a long time and until the gauge visually dropped below 3/4 on the gauge.

To me it looks like the sender can only be installed one way (or perhaps 180 degrees in the other direction). I didn’t want to force it since there are plastic tabs that hold it in place. It seems to just want to go easier in the original position.

Based on my experiment, the gauge / sender should be installed with the Full mark being at 3 o’clock on a horizontal tank and there is no adjustment that can be made. I would also say the most accurate reading is probably on the gauge itself.... but I can’t confirm that to be true.

All that being said, this would be a good way to verify the electrical sending unit is sending the proper signal back to the inside display panel with the propane level reading.

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Old 10-06-2020, 07:13 PM   #13
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The pic for gauge is taken so you can read gauge it is at 3/4 full. Just filled tank. The second pic is the monitor panel inside coach it is reading "Disc". The sensor outside cannot be "adjusted" one way or the other. It says it is a Manchester tank LP Sensor.
This has happened before and it resolved itself.
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Old 10-06-2020, 08:05 PM   #14
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Originally Posted by Windsport_29_M View Post
The pic for gauge is taken so you can read gauge it is at 3/4 full. Just filled tank. The second pic is the monitor panel inside coach it is reading "Disc". The sensor outside cannot be "adjusted" one way or the other. It says it is a Manchester tank LP Sensor.
This has happened before and it resolved itself.
Any suggestions?Attachment 26529Attachment 26532

Did you try removing the sensor and repositioning like I did in my experiment to see if your display changes? Might be worth a try.
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Old 10-06-2020, 08:13 PM   #15
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Hi thank you for your response.
The sensor has plastic clips holding it on. Is your sensor held on the same way?
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Old 10-06-2020, 08:15 PM   #16
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Also the sensor is showing full and monitor in coach is on empty "Disc".
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Old 10-06-2020, 08:16 PM   #17
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Hey I get what you are saying. I'll try it and let you know.
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Old 10-06-2020, 08:35 PM   #18
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Hi thank you for your response.
The sensor has plastic clips holding it on. Is your sensor held on the same way?
That is correct. It has three plastic clips / fingers that hold it to the pentagonal fitting on the tank.

Be careful trying to reposition it. I think it really is meant to only go on one way so you don't want to break the clips.

You could just hold the sender against the pentagonal fitting and rotate it with your hand while someone inside sees if the level changes. The gauge should move as you rotate it and the level inside should change as well.

That will tell you that the sending unit is registering the different levels and the the inside display is getting that data.
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Old 10-07-2020, 12:48 PM   #19
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LPG guage and control panel don't match.

I found an easy way to troubleshoot the guage without breaking the clips. Disconnect the gauge from the wire to the panel ( cut) short the leads from the panel together. should read 0 on the panel. open the wires, should indicate full and put a 44 or close to it ohm resister across the panel leads, it should indicate 1/2 full. It might be hard to get a resistor unless you have dabbled in electronics and have some spares laing around. Turns out it was the variable resistor in the guage that was faulty. Thanks to all for your Reponses.
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Old 10-07-2020, 01:05 PM   #20
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Thanks for letting us know what you found, and congratulations on fixing it!
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