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Question does the fuse only blow when towing or will it blow when stationary .

atb

Wizard

We have today discovered that the fuse only blows when the caravan is on the towball.  As it is lowered down, with the lights switched on, as soon as the A frame hitch hits the towball on the car, the fuse blows.  

Think we have eliminated the car as a problem - towed another van with it, no problem.  Hooked up a different car to the van, same thing happened.

If we just hook up the electrics from the van to the car, all the lights work perfectly.  It's only when the towball is attached.  HELP

Just another thought.  OH thought there could be a problem with the main earthing point on the chassis of the van.  Found it, cleaned it up, refixed it.  Still blowing the fuses. 

Is there only one earthing point on a caravan?

Check your wiring diagram, it is very unlikely the earth on pin 3 of the 12N plug will be connected to the chassis of the caravan. In which case, the fault is the live of the sidelight (pins 5 or 7 of the 12N plug) is shorting to the caravan chassis. You will need to check the wiring very carefully at each point the lighting cable/loom passes anywhere near the chassis. Another point to look at is if the sidelight is shorting to the mains earth or the gas pipe anywhere along the line. These are earthed to the chassis.

The problem will not be the caravan earthing point, obviously that is fine.

Perform the same multimeter checks I gave  above except use the caravan chassis earth instead of using pin 3 on the 12N plug as one of the test points.

The good news is, this explains why the caravan passed its annual service without problem.

Update...it's fixed.

Caravan workshop had done awning rail resealing for us last year...same workshop we returned it to this time for the wiring.  Turns out when the rails were screwed back into position, one of the screws went into the wiring!!!  

To be fair to the workshop people, they have had the van now for about 14 days, checked everything and eventually found the problem...admitted it was their mistake in the way the repair was done on the awning rail and fixed it all in time for our holidays.  I know we have had a lot of hassle trying to sort it, but at least they have put their hands up and fixed the van....I suppose sometimes these things happen.

Anyway, off on hols tomorrow, fully illuminated.  Thanks for all the good advice.

That's great news Patches , glad to hear it's sorted at last .
Have a great holiday .

atb

Wizard

Glad its now sorted and enjoy your holiday.

Regards....Turnaround

Had a great holiday and we needed the lights on the way there...it was pouring with rain and very dark!