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Check the shortstop breaker on the front near the battery. It may have been damaged or tripped if you have a manual model. You mentioned replacing the reverse polarity fuses in the load center...........there are two. Please get back to me if we need to dig deeper into this. All follow ups are included in our fee. No time limit. See a photo of one at the attached link. https://tse1.mm.bing.net/th?&id=OIP.M60cddf5db924d363dd03f6ba05cd33d0o0&w=300&h=300&c=0&pid=1.9&rs=0&p=0&r=0
It should be underneath...........either on the inside of the frame OR sometimes they put it under the belly and have a small piece of plastic that is held on with screws and you access it from there. I had forgotten that this WFCO unit only has one reverse polarity fuse. Don't see these much. a 12 VDC test light or small digital multimeter is helpful for diagnosing this sort of problem. About $5 and $20 respectively at most hardware stores and easy to use. Get back to me if we need to go further.
You can follow the current with those and see where you have it and where you don't. Look and see if there is a place to open up the belly where the wires go into it. By code, these HAVE to be within 18" of the battery. And if you have power when you hook up the shore power then the converter is working. So far as wiring diagrams..........some manufacturers have them available and some don't. Check with their Customer Service and see.
The battery isn't the issue. It has to be in the line from the battery to the load center. IF you take a test light or meter and check for power AT the load center without any shore power and you don't see any AT the battery lead then you know where to look. Doubtful they would have put the shortstop breaker or fuse behind the load center, but I suppose it is possible. Some of the people assembling these have no idea what they are doing. I can help you solve this much faster with a phone chat I think.
Hard to teach you much this way.......one reason the phone service is so popular. No limit on time or number of calls, but you may just be better off calling in a mobile tech to assist you. Sorry we didn't get to work this out.
We reached an answer..........you just didn't know how to proceed with the testing. You can ask Customer Service for a refund if you want. This service works pretty well for most customer who can do some "hands on" work and follow some guidelines, but not all.