Parasitic draw

1976 JEEP WAGONEER
75,000 MILES • 5.9L • V8 • 4WD • AUTOMATIC
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JAMES GALLAGHER
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  • 1 POST
Voltage draw with auto off drains battery.
Pulling fuses did not find problem.
Green wire from ignition module to alternator is hot. Disconnected from alternator solves 'short' draw issue.
Is it the alternator diodes or the ignition module?
How do I figure this out?
Mar 31, 2020 at 3:32 PM
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CJ MEDEVAC
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  • 11,004 POSTS
Check your voltage (cold).

Maybe remove the wires off of the alternator.

Check the voltage again tomorrow (cold).

The Medic
Mar 31, 2020 at 4:12 PM
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ASEMASTER6371
  • CERTIFIED EXPERT
  • 52,796 POSTS
Good evening,

Voltage does not cause a drain, current flow does. You need to put a voltmeter between the negative cable and the battery post. Set your meter to amp scale and get the reading.

https://www.2carpros.com/articles/car-battery-dead-overnight

It should be 50 to 75 milli amps. If you have more, remove the fuses one at a time until the current drops to normal. That will include the alternator.

If it is the alternator as you think, then it has to be replaced.

Roy

Mar 31, 2020 at 4:36 PM
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CJ MEDEVAC
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ASEMASTER6371.

I was in a hurry when I posted (wife wanting to drag me everywhere in town before they lock us down).

I meant for him to check the battery voltage before and after losing the alternator.

Glad you posted after me!

The Medic
Mar 31, 2020 at 5:25 PM