There could be several causes to your problem. The first thing you need to do is check for blown fuses. Check all of the wiring at the batteries for loose or disconnected wires. There may also be an in-line fuse or fusible link in the wiring leading to your House Batteries.
There is also a chance that the alternator is sending power to the house batteries but the batteries are not accepting the charge. Check and replenish the electrolytes in your house batteries.
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