if you're getting a 'low voltage' warning, then it's certainly not your fuse, as nothing would work at all if it was blown, but it is a notice that your HOUSE batteries, which power the hydraulic jacks/legs, are low - maybe too low to move the legs, or move them once they reach the ground and have the weight of the coach on them. It doesn't mean you can't still try to move them if you use the 'MANUAL' method, but the 'AUTO' will probably not activate until the HOUSE batteries have enough charge, either by the Alternator charging them, the Generator, or Shore Power.
Many times when a coach has sat around for a while, especially more than several days, the 'low voltage' notice light will come on. Usually after you've traveled for some time, and you get ready to park and deploy the legs, you don't see the warning because you alternator has been charging the batteries during that time.
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