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RE: Finding open/shorts in car electrical system

To: shop-talk@autox.team.net
Subject: RE: Finding open/shorts in car electrical system
From: "John T. Blair" <jblair1948@cox.net>
Date: Tue, 19 Dec 2006 21:20:02 -0500
At 05:53 PM 12/19/2006 -0800, you wrote:
>
>> Anyway, once you've pulled all the fuses, and found what 
>> circuit you have a
>> short in
>> how do you all find the short in the harness.
>
>Basic idea is to run current through the circuit but limit heat dissipation;
>then use something to detect the current.  JZ Witless used to sell a flasher
>thing that would replace the fuse, and a moving vane meter that was
>sensitive to magnetic fields.  I've done something similar using an old
>headlight bulb to limit the current, and a boy scout magnetic compass to
>detect the magnetic field.
>
>> Same goes for an open.  You've got something that doesn't 
>> work, how do you
>> find where
>> the break in the wire is?
>
>You can pick up a toner & probe for just about $50 if you shop around ...
>
>Looks like JCW still has the short detector :
>http://masl.to/?I2CE1166E
>or if that doesn't work, go to 
>http://www.jcwhitney.com
>and search for "short circuit finder".

Randall,

Thanks.  I haven't been able to access JC Whitney.  But I did a search
a while back for the telephone toners.  Got quite a list ranging from
about $70 up.  I was thinking about this one:

http://www.contractor-books.com/EX/40180.htm
RC-EX-40180 Tone Generator and Amplifier Probe Kit - $79.99

For the application at my dad's and probably the cars, we needed a
self powered toner to make the line hot.  Then using the wand follow
the tone until we found the problem.  In the car, I'd think that you'd
loose the signal at the break or short.  But haven't tried it yet.

I like you idea of the light and the compass.  Very ingenious!!!

John

John T. Blair  WA4OHZ     email:  jblair1948@cox.net
Va. Beach, Va             (eBay id: zebra48-1)
Phone:  (757) 495-8229

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