Join Date: Oct 2007
My Motorhome: Swift Kontiki 615
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Our Swift has a fuse (actually 2 but more on that later) with associated relay in a black box up above the engine, behind the air filter under the scuttle. The two fuses and relays control the 12v supply which of course, only works when the engine is running, to the fridge and the autoretracting step.
The radio has two fuses which are shown in the wiring diagram, one for the permanent supply and one for the switched supply. It would be worth checking both of those.
If both went off together it either means someone has changed the wiring (badly) or there is a more general fault.
I hope that may help you.
Any typo that I make means the errorists win.
Any comments above are only MY OPINION
and should be read as that.