The proper way to diagnose a short?

[Ghoste]

What is the proper method to do this?  Not being well versed in elctrical diagnosis I have always isolated shorts by disconnecting things until I no longer get a spark when I try to connect the ground on the battery.  This works in its own crude fashion but I know it isn't the right way to do it.

[ODZKing]

My tech referred me to a fellow who owns Syracuse Auto Electric.  This fellow has what he called a "short finder" which is something he looks to a specific portion like a tail lamp for example, and tells if it is shorted and where it is apparently. Git me by the curlies ... I'd never heard of such a thing.
Rather than spend all $$ I did what you did and simply unplugged everything and one at a time plugged them back in until it blew the fuse.
I found it!   

[Ghoste]

Gotta be a better way than we are using. 

[Cooter]

Look for the smoke Ghoste...

[Ghoste]

   Not necessarily true though.

[el dub]

You need a wiring diagram so you can find out where your wires come from and go to. It's wire checking combined with common sense. Basically you disconnect both ends of a wire. Put your multimeter on ohms. Put one lead of your meter on the end of the wire and the other to ground. If you read continuity on your meter the wire is grounded. Make sure the other end is not touching ground, use tape. Hope that helps.

[Ghoste]

So really not unlike how I have done it except that the proper way is to use a multimeter and not a spark.

[el dub]

Well some shorts won't make a spark at the battery but will eventually drain it.
You can also use a megger to see if your insulation is breaking down somewhere.
Don't forget to disconnect your positive batt cable

[nascarxx29]

I always used the testlight in between the battery cable .And pulling fuses or unplugging anything that carries power.Until testlight is not lit

[Dino]

Since something would either have to stop working completely or go haywire to have shorted, I find that isolating that circuit works best as a first step to narrow it down.  When the instrument cluster for instance is acting up or is half dead, you can look up the wiring diagram to find what feeds the system.  That's your first place to go.  I use a continuity tester first.  I never power up the system to see where it may spark.  That may be the last thing you ever do to the car.

When a certain circuit passes the test then you start eliminating things real quick and before long you will have found the issue.  You may not have the best access to it to repair it, but you'll have a pretty good idea where the problem lies.

[RGA]

The proper way to find a "draw " that kills a battery is to hook up an AMP meter in series between the neg battery cable and the negative battery post. This will give you the Amps of the draw and you can determine what is the cause by isolating each curcuit (pulling fuses, unplugging components,). If you don't have an amp meter use a test light but not as accurate and a small draw won't light the bulb.

A short is when a curcuit is touching something it's not supposed to.
Short to power = power supplied to a curcuit from alternate source and something is stuck on.
Short to ground= ground supplied to a curcuit from alternate source and can blow fuses .  

[Scaregrabber]

"I always used the testlight in between the battery cable .And pulling fuses or unplugging anything that carries power.Until testlight is not lit"

This. Fast and easy, weirdest one I ever had was a seatbelt buzzer in my 70 Challenger that would drain the battery over a 2 week period. I scratched my head for months on that one, I used the testlight method and found it in about 5 minutes.

Sheldon

[flyinlow]

A true short is an unintentional low resistance circuit.  You drop a wrench across the battery terminals for example.  There are four ways a short can resolve itself:

1. the fuse protecting the circuit opens

2. the fusible link protecting the system opens

3. the wiring involved heats up raising the resistance, limiting the current. Usually involves smoke , wiring damage and possible fire

4. if the shorted circuit involves large conductors , the battery's internal resistance will provide the circuit limiting resistance . This will involve smoke , probably fire and battery damage.

A glove box light staying on can be trouble shot with a multi meter or test light. (this is not a short circuit)

To test a true short I use a test light . This requires isolation and lots of visual inspection.( tail light wiring insulation damaged and the conductor touching the trunk floor, for example)

Once you think it is repaired ,you can also power the circuit thru a test lead with a fuse installed.