Its happening all again :( Fuse STILL blowing??

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Fireman Ash
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Wed May 13, 2009 12:06 pm

mmmmm..... :( so maybe my joys may be short lived!! :cry:

Fireman Ash
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Mon May 25, 2009 7:55 pm

Was out today in the glorious sun hoping that after changing the rear brake switch, a few connectors and a length of wire my electrical fuse blowing problems were over...wrong . getting pretty frustrating now as basically once my fuse goes I have no lights etc. and with the MOT looming next week need to get it sorted. :?

Replaced the motoplat rec/reg with a spare that I had (just incase it was that producing too much current - im guessing that what blows fuses is it?) and the output reading seemed ok however if I've got an intermittent short somewhere that may only occur when I'm out again riding e.g. broken wire. But will a continuity test help to tell me if wires are broken? have tested all and found them all ok.

Can anybody out there who is electrically minded offer a logical way to elliminate some of the more obvious causes please? Im struggling a bit now with my limited knowledge :(

Driving me nuts now...as they always do.... :x

Cheers
Ash, Torquay

firekdp
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Mon May 25, 2009 8:39 pm

Ash, it's not necessarily a continuity problem, it's normally a component failure or insulation damage that causes a short. If, when your fuse isn't blowing, all circuits work then all your wires must still be connected and the problem will probably be where the insulation has been compromised allowing a live wire to contact the frame/earth.

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sean brady scooters
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Mon May 25, 2009 8:45 pm

i,d check your loom where it runs from the steering column to bars..................
Sean Brady Scooters - 01765 690 698

Fireman Ash
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Tue May 26, 2009 10:32 am

Ok thanks for that. It's not anything from the lighting circuit causing it ( I think) as I've not had the lights on when the fuses have normally blown. I thought it may have been brake light related as it seemed to occur around the time I was downshifting and braking to a junction.

I guess it could be around the steering column as I do remember having to put on a tie wrap around the upper part (under the horncast) as they were catching. Maybe the tie was too tight and has damaged the loom as it heads up into the headset...mmm....I wonder??? :?

Thanks again for your help....IOW'll soon be here and it would be nice to have some lights!! :shock:

firekdp
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Tue May 26, 2009 10:40 am

Just because the lights aren't on doesn't mean that the short isn't on the lighting circuit. If the fault is in the supply wire to the switch it doesn't matter whether the switch is in the on or off position. If the fault is in the wire between the switch and the load then yes the switch has to be in the on position for the short to occur.

Fireman Ash
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Tue May 26, 2009 1:47 pm

I have spent many an hour continuity testing looking for breaks but all seems ok (obviously it isn't) so maybe I need to go back to the drawing board and do some more. I'm pretty sure it can't be major as I did spend some time riding it before this started. Happy Days :shock:

Thanks again

firekdp
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Tue May 26, 2009 1:54 pm

Continuity testing isn't going to find your fault as bad joints/broken wires don't blow fuses. What you should be doing is insulation testing, trying to find a low resistance to earth where there shouldn't be.

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coaster
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Tue May 26, 2009 3:31 pm

firekdp wrote:Continuity testing isn't going to find your fault as bad joints/broken wires don't blow fuses. What you should be doing is insulation testing, trying to find a low resistance to earth where there shouldn't be.
This what I was alluding to on your other thread on the lcgb forum Ash when I suggested have a good look at that rear junction box, they are often a bit crusty in there due to where they live.

Fireman Ash
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Tue May 26, 2009 3:51 pm

Sorry chaps for seeming really thick on that one. So excuse my ignorance but how do I do that? Can I use my multimeter to test for resistance?

My junction box is a motoplat reg/rectifier and has come off of a running scoot

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