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JohnJill

No 12 Volts Unless Plugged In

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Ok here I go again. We lost our energy management system control board on the 50 amp side. 12 volts still worked unplugged gen set ran and powered up. Had a new board put in now nothing. No 12volt unless plugged in gen starts with motor running dies when main motor is shut off.

Another dealer said that the board had to be replace with the same board number that is on the back, The new on is a Interllic model 620 board number 32068 and the original is a model 620 board number 27059. Could that really be the problem?

Thanks Again

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John, the different numbers, generally mean there has been an update or change to the circuit(s) on the board.

Could you post the Make, Model and Year of your coach?

Rich.

You could contact,Intellitec

Dealer / Supplier

Mastertech Inc, Marshall, Michigan

800-848-0558

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Thanks John, Forgot to ask, when the new board was installed; where the jumpers wires / connections set up- configured like the defective one?

Did you get an Owners Manual for the EMS system with the Coach? There are 3 models of the system. The 700 series, 800 series, and 900 series.

They are all about the same with some programing setup's being different.

One thing I need to check into. I kind of remember reading something related to the Winnebago EMS ?

Rich.

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John, found the electrical drawings for your coach. Both the 110 volt AC and the 12 volt DC.

Have gone through the 110volt wiring drawing in relation to the 620 EMS system. The fallowing information covers that portion of the wiring, with my thoughts as to what is causing the loose of 12 volts when not connected to shore or generator power.

Working from information supplied in your original post !!!!

Shore power and the generator power feed the main load center. So the transfer switch circuit has to be working.

Circuits L1 and L2 go to 50 amp circuit breakers in this box.

The 30 amp circuit breaker in the load center supplies power to the Inverter / Charger. THERE is a switch is the circuit to turn on the inverter. this circuit then powers the inverter / charger.

From your post it sounds like you have 12 volts from both the shore and generator supplies.

That would mean that the 12 volt charger is working and should be supplying 12 volts and charging the Coach batteries.

So, What is the voltage reading of the coach batteries ?

Measure the voltage with a 50 amp source(Shore or generator)supplying power to the inverter.

What is the reading ?

Disconnect the AC feeding the coach. Read the coach batteries volt again.

What are you reading?

NOW, with no 12 volts DC present, the batteries are bad, connected improperly or there is a wire / circuit not connected from the batteries and the 12 volt power panel.

Bad 12 volt disconnect SW. ? not really because you have voltage when connected to an AC source.

That fact makes me think there is something wired wrong, somewhere between coach batteries or a circuit / fuse somewhere that is not keeping the disconnect circuit powered.

Where is that wire or part causing the problem !

Remember the EMS system is not connected in any way to the 12 volt circuits ! It just manages the AC power load>

Rich.

Other thoughts.

Has someone worked on or modified the AC circuits ?

Did someone reconnect the inverter to the EMS circuit at some point?

Relay #2 on the EMS unit is powered from a 15 amp circuit breaker located in the inverter breaker panel. There are 5 - 15 amp circuits. Those 5 circuits allow the EMS to shed items when the coach is connected to a 30 amp shore power source and you will only have one AC unit that will run !!!

Edit- 7/13. Have you checked all the 12 volt- 55 amp circuit breakers in the main DC power panel ?

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Could it be a bad solenoid connected to the auxillary battery switch? It is what went south in my coach recently. Replaced the solenoid and all is well.

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Wayne, Rich- One would think that was the problem. The strange thing is, John has 12 volts whenever connected to Shore power or the Generator is running. That is what I'm getting from his post!

By chance did you experience the same symptoms?

Rich.

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12 volts when plugged, or generator, is probably from the converter, or inverter/converter. Sure sounds like a solenoid not making up for some reason, possibly bad, or master switch bad. Could even be a bad, or incorrectly wired battery isolator, if the coach has one, most do.

Maybe a jumper from battery bank directly to the 12 volt side of the converter for trouble shooting purposes, that is of course the battery bank has already been deemed to have proper voltage, 12.6 or above.

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Wayne, Rich- One would think that was the problem. The strange thing is, John has 12 volts whenever connected to Shore power or the Generator is running. That is what I'm getting from his post!

By chance did you experience the same symptoms?

Rich.

Rich,

It happened to me prior to this trip. We headed to Dallas, then Arkansas and along the way my EMS would beep loudly and I would loose 12 power going down the highway. Eventually it stopped altogether. I called the factory and they suggested it was the auxiliary switch solenoid that cuts the 12v off and on. The solenoid on my coach is behind a panel in my electrical bay. The dealer replaced it and all is as should be now. So yes, hooked up to power or running the generator I had 12v, but as soon as I was on house power only the 12v was non-existent.

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Thanks Wayne! John has a 2006 39F Itasca Meridian.

So now I will look and see if there is a similar relay circuit in his unit. Sure the wiring is very close.

Know there is a disconnect solenoid circuit for the 12 volt system.

Rich.

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Thanks Wayne! John has a 2006 39F Itasca Meridian.

So now I will look and see if there is a similar relay circuit in his unit. Sure the wiring is very close.

Know there is a disconnect solenoid circuit for the 12 volt system.

Rich.

My money at this time would be a quick check of the disconnect solenoid. A bypass of that solenoid should be an easy check to see if the 12v comes back on. In my particular case, tapping on the solenoid caused it to cut in and out.

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