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These should be wired up in a "series-parallel" connection and I suspect that is what you see here. Each pair is wired up first in series........that is the positive of one to the negative of the other. That gives you one "12 VDC unit" consisting of two batteries. Then the other pair is wired up the same way. Once you have two "units" as described, you parallel them by hooking up the OPEN positive terminals together and then the OPEN negative terminals together. That keeps the DC voltage at 12 VDC. Then you hook up the coach cables. The positive cable(s) go to one of the positives that you just hooked together. Lastly, you hook up the negative cable(s) to one of the negatives that you just hooked together and it is best to hook them up to the OTHER pair rather than hooking them up to the same pair as the positive feed(s). The solenoid you see if for hooking this whole group of batteries to the chassis batteries for extra starting power in case then are dead so you aren't stranded. It is NOT the battery disconnect switch, but the "Aux Start" rocker switch.........usually on the dash someplace. Hope that helps. This can be very confusing to someone who doesn't do this all the time or is familiar with these batteries in larger Class A coaches. Please get back to me if you need more on this as all follow ups are included and expected here. I am also making the phone chat option available for you in case you feel that would be more helpful.
I am attaching some Fleetwood wiring diagrams showing this. You want the one for the "Square" formation. Print these out so you have them later. Very handy! http://ww2.justanswer.com/uploads/michaelreush/2009-03-11_030420_Chassis_Electrical_03_fleetwood.pdf
Just checking back in to see if you found this information helpful and if you needed any more input on this from me?