main fuse keeps blowing

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main fuse keeps blowing

Postby bay1972 » Sun Aug 05, 2012 2:54 pm

can anybody help main fuse keeps blowing every time i try to attach battery terminals. still have hazards but nothing else all worked fine before welding
will confess did not remove earth cable rembered after about 10 minutes could i have blown something . van cannot be moved as on axle stands. if cannot solve does anybody know a mobile vehical electrican.

cheers lee
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Postby SiC » Sun Aug 05, 2012 4:55 pm

Voltage regulator blown? Too coincidental that you welded without disconnecting and it worked before?

Where were you welding? You not melted and shorted something?

When you say main fuse which one specifically?

What vehicle? Bug or bus? I guess latter from username

I wouldn't go calling an auto electrician just yet!
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Postby bay1972 » Sun Aug 05, 2012 7:35 pm

cheers for getting back vehical bus welding floor pan chassis, will try changing regulator first check main wiring loom under floor pan cannot see any tears or burns in outer sleeve. main fuse which i think is the main live in as nothing else other than hazards will work .

cheers
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Postby SiC » Sun Aug 05, 2012 9:03 pm

Check in engine bay when you disconnected battery you haven't knocked any engine wiring, check coil and carb specifically....
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Postby bay1972 » Wed Aug 08, 2012 7:27 pm

Checked all wiring in engine compartment cannot see anything loose changed voltage regulator. Still blows fuses. Not sure where else to look
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Postby caveman » Wed Aug 08, 2012 7:35 pm

you could try taking out all but one of the fuses then trying to see if it still blows if not try the next fuse untiull you have identified the fuse that the problem is on - then you have the circuit that has the problem - using a wiring diagram you can trace what is on it and look for a problem there
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Postby GBHgpJON » Wed Aug 08, 2012 7:35 pm

Have you tried a different battery.......no expert here, but perhaps it got cooked and is shorting internally????
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Postby SiC » Wed Aug 08, 2012 8:10 pm

Yeah Jon fair point, could have twisted a plate in the battery but normally when this happens it normally just flattens battery (in my limited experience of it!)...

Are you connecting battery right way?

You say the fuse blows as soon as you connect? Is this with ignition off?! The only thing which would be live is hazards, side lights, interior light and maybe stereo??

Can you confirm if it is with ignition off and just when connect up?!?
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Postby GBHgpJON » Wed Aug 08, 2012 8:16 pm

SiC wrote: The only thing which would be live is hazards, side lights, interior light and maybe stereo??


Good question Si...
Heh.......dont forget, this is a VW......anything is possible!
i.e.....The stop lights on my T25 work without the ignition on :lol:
So dont assume anything!!! :wink:
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Postby SiC » Wed Aug 08, 2012 8:31 pm

Haha fair point dude! I still don't understand what the "main" fuse is?!
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Postby bay1972 » Wed Aug 08, 2012 8:54 pm

cheers all for replying i have isolated which fuse it is after discovering the fuse fuse box has been put in up side down. looking on the back fuse box i think it is the main power wire which runs the ignition. i have interior lights which work the head lights flash and have hazards. i have a brand new battery fitted. disconnected wires from ignition still blows fuse but if you take the wires that connect to fuse box end out fuse ok.
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Postby SiC » Wed Aug 08, 2012 9:02 pm

Erm it kinda would be as you've disconnected the fuse/broke the circuit!

So you've established which circuit...

As asked before does it blow as soon as battery connected or when you turn key?

If its just with battery connected I'm confused, if it's when you turn ignition on then more possibilities....

Any wires running where you were welding? Not melted insulation off main power from battery to fuse box? Olny thing I can think is that the main live is shorting if it blows as soon as you touch battery on...
I don't know if the main live earthing on chassis would blow fuse?
If this is the case it can only be due something done while working on it...

If its at ignition on position then maybe coil? Or fuel cut off solenoid on carb?
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Postby SiC » Wed Aug 08, 2012 9:08 pm

Ok I defo think the main power wire from battery to fuse box is shorting in body or chassis, most likey due to damaged or melted insulation!

Check at battery end where you have disconnected and reconnected

Check everywhere you welded

Check at fuse box end that its not catching body

Then work along I guess
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Postby bay1972 » Wed Aug 08, 2012 9:33 pm

cheers it blows when ignition switched off as you say may have melted main live when welding . could this have been when battery was connected when welding wire may have overheated.
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Postby SiC » Wed Aug 08, 2012 9:39 pm

I would not think so... Normally only kill electronics, diodes in modern alternators, ecus etc....

More likely just be melted from heat if you've welded near it?
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