Is this a fuse on the negative?

Doogal Too · Mar 16, 2024

Just got my 1979 Santana series 3 109 station wagon. I took it out for a few miles and came back to snoop around inside. When I went to start it back up to park it, no power whatsoever. No lights… nothing. I took the battery out and charged it to be sure that wasn’t it. Nope. Fuses inside were all fine. I discovered it was this little box that splits the earth cable between the battery and engine block. I’m guessing it’s a fuse but I’ve never seen one like it and never on the negative side. Looking to be educated by the experts!

Doogal Too · Mar 16, 2024

Doogal Too said:
Just got my 1979 Santana series 3 109 station wagon. I took it out for a few miles and came back to snoop around inside. When I went to start it back up to park it, no power whatsoever. No lights… nothing. I took the battery out and charged it to be sure that wasn’t it. Nope. Fuses inside were all fine. I discovered it was this little box that splits the earth cable between the battery and engine block. I’m guessing it’s a fuse but I’ve never seen one like it and never on the negative side. Looking to be educated by the experts!

Diesel by the way

Graculus · Mar 16, 2024

That looks like an isolator switch, is there a 'T' handle on the other side of the bulkhead?.

steve2286w · Mar 16, 2024

Never seen one but Top bit looks like it screws on so can’t turn, perhaps it’s like a bimetallic strip that breaks circuit if it gets overheated , is there heat damage on the bit you’re holding

Doogal Too · Mar 16, 2024

Graculus said:
That looks like an isolator switch, is there a 'T' handle on the other side of the bulkhead?.

There is. How does it work? Obviously I turned it, causing the problem and I tried to turn it back. So I’m guessing I’m either using it wrong or I may have have broken it.

steve2286w · Mar 17, 2024

So maybe when you turn the handle the copper bar moves in and out breaking circuit.?

Graculus · Mar 17, 2024

Doogal Too said:
There is. How does it work? Obviously I turned it, causing the problem and I tried to turn it back. So I’m guessing I’m either using it wrong or I may have have broken it.

There may be a spring detent, try pushing or pulling the handle whilst turning - or it could just be really stiff due to lack of use.
You could always just put all the wiring on to one of the terminals which would bypass the switch and restore the circuit continuity.

mystery · Mar 17, 2024

just put both cable lugs on one stud until you sort the problem

Doogal Too · Mar 18, 2024

Thanks everyone. Your advice and insights were invaluable.

Is this a fuse on the negative?

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