Finding a short.

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Finding a short.

Postby <367b.html?mode=viewprofile&u=54">Blindstitch2002 » Tue Jun 08, 2010 4:39 am

Edit......
Larry just sent me some photos to spice this up a bit. So here's Larry.

Here is a few pictures of the bulb type circuit short finder I made.

Put the clips on each side of where the fuse goes that's popping.

Turn on the key and it will light up as long as there is a short in the circuit. I have it hooked to the horn and turn signal circuit. And I directly shorted out the horn to ground to show it light up.

When the short is found and fixed the light will go out.

Image

Image

Image








Original post.....

I know this is in the quick reference but it's a sorry excuse. I took the bike out for a run today and got about 8-10 miles from home and was turning around. Got a short way down the road and the main fuse blew. Confused me for a second but once I saw I didn't have lights I knew where to check. Well I tired a new fews and it lasted about a second. For grins I tried another one and same thing. Because I was farther away than I wanted to be from home I tried a 30 watt fuse and it got me about 10 feet before it blew.

So I finally got through to someone and got my truck and loaded the bike. Now I'm pretty sure I have a short somewhere so how should I go about finding it. It's tomorrows project.
Last edited by <367b.html?mode=viewprofile&u=54">Blindstitch2002 on Mon Jun 14, 2010 5:47 am, edited 1 time in total.
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Re: Finding a short.

Postby <65cc.html?mode=viewprofile&u=410">spanish bandit » Tue Jun 08, 2010 8:15 am

For grins I tried another one and same thing. Because I was farther away than I wanted to be from home I tried a 30 watt fuse and it got me about 10 feet before it blew.......................................
don i take it you mean 3o amp,not 30 watt.
if your blowing 30 amp,id say you have a definate live to earth.
shame daves not here[yet ;) ]
here,in case you dont have it is daves link on t.s. http://www.genebitsystems.com/david/MotorcycleElectrical/index.htm

id be searching in and around the light wiring.id pull every connector i could see,put a new 5amp fuse in.then start putting them in one by one,trying the lights every time.a process of ilimination.

dave posted a good way using a bulb connected with 2 wires wired in series
good luck
uk 1982 gli silverwing
uk,1981 gl troublemaker

when i feel the need,i do it
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Re: Finding a short.

Postby Gman » Tue Jun 08, 2010 8:24 am

Electrical fault finding is one of the hardest jobs.I'm lucky inasmuch as I'm trained in it(Certificates in electronic servicing).

Listen when very quiet.Sometimes an arcing sound/crackle can give away the location as can heat around a wire.Look for scorching/melted wires and Bad grounds on the Earthing wires.

Blowing 30 amps mean it's usually on the main power supply wire.Check the schematics you posted BS.I think it's the thick red on most of the bikes.Start at the battery and work your way forward around the solenoid/starter relay.If the lighting fuses didn't blow it's most likely on the main supply.Also check the main multi-plug connectors for the above.Even a badly corroded spade connector in them can cause arcing and massive current draw especially if broken inside them.
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Re: Finding a short.

Postby <367b.html?mode=viewprofile&u=54">Blindstitch2002 » Tue Jun 08, 2010 9:53 am

spanish bandit wrote:dave posted a good way using a bulb connected with 2 wires wired in series
good luck


That's the one I was thinking of.

I thought it said to connect a bulb with two wires where the main fuse would be and then pull plug till it goes out.

I do have a bulb with alligator clips ready to do once I find the directions or wake up in 5 hours.
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Re: Finding a short.

Postby <367b.html?mode=viewprofile&u=54">Blindstitch2002 » Tue Jun 08, 2010 10:50 am

Here's what I was looking for.

DaveF wrote:
There is a short to ground someplace.

Here's one way to proceed. Replace the main fuse with a 12 volt bulb. The bulb will be lit as long as the short is present. Then start disconnecting things until the bulb is no longer lit to find out what is shorted. A wire may also be pinched or shorted to ground - try wiggling the various wires and cables.

Another test method is to use an ohmmeter to methodically trace out the short using a wiring diagram as a guide.



The joy about CC being down is if you do a google search and select cached instead of link a lot of the info is still there.
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Re: Finding a short.

Postby Gman » Tue Jun 08, 2010 11:22 am

That's an excellent technique.I use my multimeter across the fuse set at 20v DC but a bulb would be easier to see.
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Re: Finding a short.

Postby <367b.html?mode=viewprofile&u=54">Blindstitch2002 » Wed Jun 09, 2010 12:45 am

I think I got the little sucker. In the headlight bucket I found a hot wire with all the protective plastic off it pressed against the bucket.
I'm not sure what the wire is yet and it was raining so I didn't want to dink around but when I pull the wire away the fuse didn't blow. Just to check it I put in a smaller fuse that didn't matter and put the wire back in the position it was in and pop goes the fuse. I wrapped it in electrical tape till I can figure out its use. I don't have front running light on my bike so I'm wondering if it may be that.

The wire is actually two yellow/brown/green wires that are connected to each other and lead into a female bullet connector.
http://i693.photobucket.com/albums/vv29 ... 1276040693
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Re: Finding a short.

Postby <65cc.html?mode=viewprofile&u=410">spanish bandit » Wed Jun 09, 2010 8:44 am

Blindstitch2002 wrote:I think I got the little sucker. In the headlight bucket I found a hot wire with all the protective plastic off it pressed against the bucket.
I'm not sure what the wire is yet and it was raining so I didn't want to dink around but when I pull the wire away the fuse didn't blow. Just to check it I put in a smaller fuse that didn't matter and put the wire back in the position it was in and pop goes the fuse. I wrapped it in electrical tape till I can figure out its use. I don't have front running light on my bike so I'm wondering if it may be that.

The wire is actually two yellow/brown/green wires that are connected to each other and lead into a female bullet connector.
http://i693.photobucket.com/albums/vv29 ... 1276040693

glad you found it don.it had to be a live direct to earth to take out the main fuse.
if its not connected to anything,its probably within the loom for auxillary[i have a couple of spare lives on mine]
uk 1982 gli silverwing
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Re: Finding a short.

Postby Gman » Wed Jun 09, 2010 10:08 am

There are usually several redundant wires in the headlight for different bike models where some are used.It's most likely one of those has become bare at some point and caused a short.The European models don't use the American forward running light convention.Our bikes only use rear indicators,stop and tail lights.
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Re: Finding a short.

Postby <367b.html?mode=viewprofile&u=54">Blindstitch2002 » Wed Jun 09, 2010 2:39 pm

Admin wrote:There are usually several redundant wires in the headlight for different bike models where some are used.It's most likely one of those has become bare at some point and caused a short.The European models don't use the American forward running light convention.Our bikes only use rear indicators,stop and tail lights.



Interesting. So you guys get more brakes and less lights. I would live without forward running light for a right brake caliper.
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