Short Circuit

[ChrisCollege]

I have a short some where that is pulling a full 12 volts when I take a reading with my multimeter between the neg post on the battery and the neg cable. I have tried pulling each fuse and disconnecting the starter power lead to see if I could isolate the draw. not the starter nor any of the fuses. Does any one know what could be creating this draw that does not go through the fuse box.

Thanks.

Chris

[Damage, Inc.]

Alternator/regulator?

[The Anti-Chrysler]

Pulling 12v isn't important. It's the amp draw. If it's in the engine bay, I would try to unplug components one at a time - including your MSD. Also try the alternator, ignition module, wiper motor, blower, etc etc.

[Joe Guilbeau]

You are reading an essentially series circuit where you open the circuit and measure the VOLTAGE, correct?...by removing the Negative Battery post and placing your meter between the post and cable termination?

The voltage reading you get better be the battery voltage. This is normal, and if you take a minute or so to think about it, it is the same test that you are performing when you remove both positive and negative cables from a battery and place the meter leads on the pos and neg terminals of the battery.

A better test in your situation is to set the meter to read AMPERES, and measure the current that is being drawn thru the Jeep when the engine is off and the key is off.

This will check for any shorts that might be draining your battery when the key is off.

Here you should only measure the current that the clock or radio needs to keep themselves active, also any alarms that you might have installed, I think that probably you should read somewhere in the range of 10-20ma, (0.010-0.020 Amps).

Did you perhaps mean you measure 12 Amps on this test, rather than voltage?

If you pull this many amps, then it is almost certainly the Alternator. Remove the alternator wires and repeat the test, if the current drain has stopped, then you have found your problem.

The diodes or SCRs in alternators are the culprit, when they start to go bad, they leak and provide a path for the current to flow, thereby draining a fully charged battery in as little time as 3-4 hours, more often overnight.

[Crazy_Jeepman]

Volt Meter would read 12 volts. Multimeter should be set to Amps, not volts.

[ChrisCollege]

Thanks. All. I was reading volts not amps my mistake. But, I did also use the test light and had a nice bright glow. I think the test light tells me that I have a short, but I should probably go back and use the multimeter on amps. Don't think it is the alternator it is 6 month old. Would the alterntor draw amps with the engine off. How would I test the alterntor.

[Crazy_Jeepman]

Light will light up as well. Simplest way to see if you have a draw is: be sure under hood light is unplugged, fuse pulled for the clock/radio. Then in the dark disconect the battery ground, and then touch it back to the battery post. If it sparks a little, there is a draw, if not, no draw. What is the reason for this, you having dead battery issues?

[Damage, Inc.]

Rule #1: DON'T THINK. As soon as you say 'I don't think it is' part blah-blah, sure as Great Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley MoogleyGreat Googley Moogley, it's going to be that part! smile.gif

[Crazy_Jeepman]

Disconect the Alternator, and see if the draw is still there. Or take it off and have it tested

[ChrisCollege]

The orginal problem is a dead battery sitting overnight.

Thanks to all. I will recheck the appropriate way.