Which fuse blown (1 Viewer)

[LL65 3NR]

Any idea which fuse keeps blowing (25A ) as soon as I replaced it.

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Brought the van yesterday! 1990 6 birth thanks for the help. Dylan

 

[Flamenca]

On my Hymer the fuse removed in your photo is the battery charger output.

 

[Badknee]

1) If you leave the fuse out what doesn't work?
2)Turn everything off and back on one by one till it blows.
3) get an auto electrician to have a look.
4) take it back.

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[LL65 3NR]

Thanks badknee, there are many things that don't work, fridge / hot water/ fire. I'll have to try chase the wire around the van then. Just thought Hymer may have fitted the fuses in the same order for all vehicles.
Cheers, Dylan

 

[LL65 3NR]

Where the hookup comes in has many connections and junction points. One reads 25v!!! Engine not running, no mains connected. I can only assume my Hymer has the two batteries in series here, why???

 

[scotjimland]

Where the hookup comes in has many connections and junction points. One reads 25v!!! Engine not running, no mains connected. I can only assume my Hymer has the two batteries in series here, why???

That certainly looks like it may be the source of the problem..further testing needed to verify..

Have a look at the leisure batters.. see how they are connected together.. .. the previous owner may have made a mistake and put them in series rather than parallel..

Meanwhile, I would pull all fuses to protect other things from having 24v applied.. they don't like 24v up 'em..

I would also ask the seller..

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[autorouter]

When you say 'One reads 25V' are you saying you have measured the voltage with a meter and it's 25V?

Have you got a solar panel? If not, with no mains connected and the engine not running, the voltage should never be more than 13.6V. A 12V battery can not supply more than 13.6V.

25V is about right for two 12V batteries in series. But I can't think of many good reasons for wiring batteries in series. Most likely to be incompetence.

One possibility: a new leisure battery, with the positive and negative terminals the opposite way round to the original battery. I'm guessing here, but I reckon you'd get 25V where the cab and leisure batteries meet (at the charger, maybe). And none of your habitation electrics would work either. Maybe the lights would work, if they're not LEDs or fluorescents.

So check, double check then triple check that your leisure battery is wired as it should be. Beware, Hymer colours are misleading. They use brown for negative and blue for positive. If you're used to MHs of other brands/nationalities you may be used to the opposite.

 

[autorouter]

There will be an isolation switch and a fuse very near the leisure battery. This should be wired to the POSITIVE (+) battery terminal, not the negative battery terminal.

 

[LL65 3NR]

Thanks for replies.
@Scotjim there is only one leisure battery, and no solar panel.

@autorouter yes I checked with a multimeter, then checked many times to make sure I wasn't reading millivolts or something daft. Nowhere else in the system yet, lights 12.6v etc. I did notice the eriba charger had brown to the negative and blue to the positive and thought I'd found the problem only to read the blue and brown in German on the charger correctly wired.

Very different to what I'm used to. I previously owned a coachbuilt vw t25 by weinsberg before building my own vw t5 from scratch to full camper with split charge, leisure batteries, solar etc so good with electrics - if I can chase the wires but this beast is a labyrinth.
There is an isolator key but that just kills everything. More ferreting and hunting tomorrow. (And I'll check the leisure polarity)

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[Flamenca]

Attached is the wiring diagram for my 1992 B564. I suspect yours should be similar.

 

[LL65 3NR]

@Flamenca your a star! Looks like more evidence towards battery charger if fuse layout same, should be. Cheers

 

[autorouter]

Check with a meter between the isolation switch terminal and a bodywork earth point. The switch should be POSITIVE 12V relative to the bodywork earth point. If it is negative, then you've found your problem. I say use a bodywork earth point to avoid all wires, which may possibly be wired incorrectly.

If you can't get at the isolation switch easily, then test at the copper metal links to the right of the first four fuses instead. The isolation switch will have to be ON to get a voltage, though.

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