01-26-2010, 03:06 PM
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#57
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GX Member
Join Date: May 2009
Location: Northwest PA
Posts: 40
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Quote:
Originally Posted by clutch1
whoah whoah whoah, ok, there's something very important you have to know about measuring voltage.
*When there is a break in the circuit (ie ground removed), you will always find voltage across that break!*
When you take the ground off, and put one lead on that neg post, you're measuring across the break, thus system voltage. If you were to put your voltmeter leads on the negative cable and one on the negative post, you will read system voltage.
That's very important to know. So is this:
The voltmeter measures drops in voltage.. or difference. When a circuit is closed and working properly, loads (resistance) with current through them "use" voltage so to speak. If you have two identical light bulbs in series, one will "use" 6V, and the other will "use" the other 6, leaving almost nothing at ground (it'll be a very minute reading, in reality). Measure across one bulb and you'll see 6 volts, because the 2 voltages will be 12 on one side, 6 on the other. Hope that makes sense.
NOW, remove ground after the 2nd bulb. No more current can flow, THUS, there's no voltage drop across the bulbs. If you measure across the break in ground you will still see 12V, because the voltage "pressure" is still there, and no current = no voltage drop across loads.
Ok i'm gonna double post here.. stay tuned.
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You are correct, that was a very dumb assumption considering I have taken a class on electrical engineering. It was a long day I guess haha. But alright, I checked the harness wires, the red "control" wire has 3.98 volts flowing through it with the engine running. Im gonna change out this fusible link now and see if that changes anything.
Last edited by greg_gorrell : 01-26-2010 at 03:30 PM.
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