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This could be a number of issues. First off Do you Know the make and Model number of the water heater?
Also when you turn the switch ON do you hear anything at all under the outside cover for the water heater??
Atwood ge16 ext. I hear nothing.
IF you are getting no noise at all, I would go to the outside and look under the cover for a thermal fuse, it should be on a brown wire it will have a clear plastic sleeve over it, if it is blown the water heater will not do anything, for testing you can put a jumper wire in it's place but only for testing. Next I would pull the harness for the control board and clean the contacts on the board with a pencil eraser, verify you are getting power on that harness, no power on that harness look inside the RV for a fuse box and check the fuses...... The control board could also be faulty and a shop can test it out with a special tester.... Robert
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