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testing for parasitic battery draw

Angie

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On the neg battery post when I take off the clamp and place it back on, I get a spark. I shouldn't get anything as this truck has no computer, no small radio memories or anything.

I have placed a voltmeter between the neg cable and the post with the wire into the 10A plug on the meter, it shows no current going through the line. I have not done the basic (pull fuses) route yet as I can not show any draw in the meter.

Is there a secondary way to confirm how to find a draw with the meter? If I place the meter on the + side of the battery post and wire will it show anything more than 12+ volts? if so what settings do I use on the meter?

thanks
 


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Shouldn't the meter be on Volts? Between the post and cable....
Then if there is no current there will be no reading. If there is reading then start pulling fuses....
 

Angie

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here is the set of directions i was following .... any advise?

 

RonD

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You can just put a 12v test light between cable and battery post, if there is current flowing it will glow

Volt meter will work as well, show a smaller voltage but not 0 volt if electrons are moving thru it

Yes, disconnect fusible links from starter relay post first to see if current flow stops, then move to engine bay fuses

Alternators can cause phantom power draws, disconnect alternator's wires and reconnect battery cable to see if spark is no longer there
 

Angie

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hi ron, yes got that light thing, but shouldn't the draw also be shown in how many amps are being used through the neg connections as well?
 

RonD

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Sure

0.03amps, or 30milliamps, is minimum with computer and radio which you don't have
Can go as high as 70milliamps with keyless entry as a steady amp draw with key off door closed

The alternator can draw a few milliamps when first connected then nothing after that with key off
Which is why I suggested disconnecting alternator to see if spark was gone

Alternators B+ wire is connected directly to the 3 fields in it's case(via diodes) these will suck in some milliamps when connected to battery, then no draw after that

Depending on year there may be a 5v power supply for the cluster that will also "charge up" when power is available, again just a quick milliamp draw then nothing after that

So hook up amp meter and then touch it to battery terminal and look for the quick draw and then no draw after that
 

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