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Fresh water fill control Question for Electronic Whizzes

Yahoo Message Number: 64136
My Magna has a fresh water fill switch. This is tied into a solenoid down in the water bay which is in turn tied into the level sensor system. When the tank is "full" according to (I think) that sensor and related series of lights on the control panel, the solenoid shuts off. One of the biggest pains in ass in this coach is that this "full" occurs minus what seems to be about 10 or 15 gallons and I have to top off the tank through the water fill door. I am assuming there is no way to tell the system to fill the rest of the way automatically, but I was wondering if it would be possible to install a switch or something at the solenoid so I could then lectrically but manually open that solenoid to fill the tank all the way. Anyone have any ideas?

Thanks.

Rich 2002 Magna

Re: Fresh water fill control Question for Electronic Whizzes

Reply #1 –
Yahoo Message Number: 64138
Rich My coach actually does the same thing but it is more like the first cut-off is nearer to 80% full. I cut a hole when the dump hose plastic enclosure, so that I can see the fresh water tank. It appears as though , when the water comes at high volume it splashes up to the sensor. I just press the fill button again and often have to do this a few times to get the tank full. As I can see the tank ( I press a flash light up against the white plastic , so that I can better the water level ) I find that the cutoff stop- start time gets shorter and the tank will be full. I only go through this , if I need the tank to be really full for a trip where I will be dry camping . If you can't get to see the tank , I would just open the manual fill connection , and that would prevent the tank from over filling if the switch did not cut it off. Hope this helps.

Ron Baran 09 Magna 7025

Re: Fresh water fill control Question for Electronic Whizzes

Reply #2 –
Yahoo Message Number: 64140
Rich...

If your Magna is wired like my ol' Magna, the "full" sensor tells the solenoid to shut off the water when the fresh-water holding tank is "Full"...
The problem is: The fresh-water holding tank is molded with rounded corners, and the sensor must be mounted on a flat surface, which makes it impossible to mount the sensor at the very top of the tank...
You could install a "toggle" switch in the wire from the "full" sensor to the solenoid to control the solenoid manually... You would also have to "bleed" the air out of the tank by opening a cold water faucet in the coach in order to let it fill completely...
Most convenient place to put the "toggle" switch would be on the monitor panel... Haven't looked behind my panel lately, but you may be able to "tap" the wire to the solenoid right there at the monitor panel... if not, there may be spare wires in the harness from the tank sensors to the monitor panel you can use, or you may have to "pull" wire to the solenoid itself in order to hook up the switch...

buck

k7wn, '99magna5653, C10, Allison 4060HD

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Re: Fresh water fill control Question for Electronic Whizzes

Reply #3 –
Yahoo Message Number: 64146
Tom, my magna is wired like yours, but once it is "full" if you then press the fill button again, the lights come on and it shuts off instantly. running wire from that switch to the solenoid is basically impossible. i am assuming that there is a microprocessor board involved. have been through manual and cannot find schematics for this system. i am assuming if you applied 12v to the correct wire at the solenoid, it would open but do not know which wire or if doing that would damage rest of electronic system involved

Rich 2002 Magna

Re: Fresh water fill control Question for Electronic Whizzes

Reply #4 –
Yahoo Message Number: 64152
I looked thru my manual Rich, and like you, don't seem to have a schematic of the solenoid hookup...
electrically speaking tho, I don't think the sensor would be able to handle enough voltage/current to open/close the circuit to the solenoid...
So, it would have to send the "tank full" signal to a circuit board that would in turn tell a relay etc. to cut the voltage to the solenoid... I think you are correct that the solenoid is normally closed and only opens when you toggle the "Fresh Water Fill" switch... So, contrary to my first thoughts, you would have to keep the voltage on the solenoid after the sensor says the tank is full and therefore could "back-feed" voltage into the circuit board and cause damage unless you use a "blocking" diode to keep the voltage out of the circuit board...

May be more trouble than it will be worth to you...

buck

k7wn, '99magna5653, C10, Allison 4060HD

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Re: Fresh water fill control Question for Electronic Whizzes

Reply #5 –
Yahoo Message Number: 64168
Thanks Buck,

That feedback to the board is what I was worried about. There has to be a board, I think. Too bad, since I dry camp a lot and need to totally fill the tank. Actually, it just occured to me that perhaps one could cut the wire to the top level sensor and put a switch on that to temporarily fool the board into thinking it was not full! I believe that when the water hits the sensor it closes a circuit or changes resistance or something like that.

Rich 2002 Magna

Re: Fresh water fill control Question for Electronic Whizzes

Reply #6 –
Yahoo Message Number: 64170
Sounds to me like a valid solution to your problem Rich... dis-connecting the "full" sensor should let the tank fill all the way...

Good Luck!

buck

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Re: Fresh water fill control Question for Electronic Whizzes

Reply #7 –
Yahoo Message Number: 64194
Last year I had to repair the Fresh Water Fill circuit board on my 1995 Magna. It has an automatic shutoff when the tank level reads full.
In the process, I documented the wiring schematic and functions as well as have some pictures of the actual wiring behind the overhead dash panel switching.
If you are interested, send me your email and I can attach the pictures and my excel spreadsheet that passes for a wiring schematic.

For what it is worth:

On my rig, the water fill circuit board sends wire 255 to an automotive relay. From that relay, wire 255 runs to the water fill solenoid and wire 177 runs to the water pump. When the board is turned on, 255 opens the solenoid and 177 starts the pump.
Wire 378 runs from the "Full" indicator switch to the water fill board. When 378 signals full, the board shuts down 177 and 255.
I suspect that if you can defeat wire 378 with a switch, you can achieve your water fill goal.
However, I seem to remember that wire 378 also sends the signal for "full" on other tankages as well so you would want to normally operate with wire 378 in a normal condition.

Dean

95 Magna 5280
 

Re: Fresh water fill control Question for Electronic Whizzes

Reply #8 –
Yahoo Message Number: 64198
In addition, wires 255 and 177 are labeled and easily identified at the utility compartment end on my rig.
I did not find 378 at that location, but I had no need to search for it.

Dean

95 Magna 5280