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Testing a wire for a short


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Posted

I am looking at buying a wire testing device. Just not sure what one I should get. I have a problem with on of my switches and have found out its not the fuse, relay, end point, or switch. They question I have, is how and what do I use to find a short in a wire harness. Specially when its from the console to the trunk area. (Its basically my switch to the top pump in my convertible is not working.)

 

Thanks for any help!

Posted

Replace the fuse with a trouble light. With key on and a short, it should light. When it goes out you found the short.

Posted

Replace the fuse with a trouble light. With key on and a short, it should light. When it goes out you found the short.

 

That's a great trick, and an old seat belt buzzer from the salvage yard instead of the light will make it a bit easier too.

If you want to but an actual tool bet a simple digital multi-meter, just make sure you get one that's auto-ranging and then never set it to measure amps until somebody explains that part to you.

I have about 4 different meters, but my little buddy meter that I reach for first is a $30 craftsman from Kmart.

Posted

Not for the hearing impaired or in a noisy environment. For those fortunate enough to be near a Harbor Fright & on their mailing list they often have a nice little DVM as a freebie. I have a pile of them.

 

At times a clamp-on DC Ammeter is needed or a capacitance meter good up to 200 mikes. Others, there is no substitute for an oscilloscope. Good instruments are as much a part of a toolbox for computer cars as any wrench.

Posted

You don't have a short circuit from the sound of it, You have an open circuit. try to lure that one friend you have that's into car audio over and have him look at it it shouldn't take more than a half hour to diagnose the entire system

Posted

Mea culpa. Thought he knew he had a short (e.g. fuse keeps blowing). Just not working can be done with a test light.

Posted

Dumb here. How would you go about testing the wire with a Light Probe? I guess where do you start from?

Posted

Well start with the 12v gozinta, hook the other end to ground, and probe until you lose the signal. For  a ground fault connect to 12v and probe from ground.

Posted

Not for the hearing impaired or in a noisy environment. For those fortunate enough to be near a Harbor Fright & on their mailing list they often have a nice little DVM as a freebie. I have a pile of them.

 

At times a clamp-on DC Ammeter is needed or a capacitance meter good up to 200 mikes. Others, there is no substitute for an oscilloscope. Good instruments are as much a part of a toolbox for computer cars as any wrench.

 

that DVM looks exactly like the one I just bought at O'Reilly's and the thing half works too.

Posted (edited)

I have  had two failure modes so far in a gaggle of them. Battery usually lasts less than a year and I've had the test leads break. Otherwise they are worth every penny of free.

Edited by Padgett

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