When I was looking for my RV, 2002-2006 Fleetwood Tiogas the dozen or so that I looked at, 75 percent had non working outside stereos,most were from water incursion, Some were just a blown fuse. That is where I would start.
Located behind the door to the fuse panel below the front facing dinette seat.
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This my fuse block on my 2006 Tioga.
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Located on that door inside, is this.
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It will tell you which fuse goes to what,that is where I would start,check each fuse and pull each connector and reset.
2006 TIOGA 26Q CHEVY 6.0 WORKHORSE VORTECFormer El Monte RV RentalRetired Teamster Local 692Buying A Rental Class C