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Parasitic draw

Tiny
JAMES GALLAGHER
  • MEMBER
  • 1976 JEEP WAGONEER
  • 5.9L
  • V8
  • 4WD
  • AUTOMATIC
  • 75,000 MILES
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?
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Tuesday, March 31st, 2020 AT 3:32 PM

3 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,005 POSTS
Check your voltage (cold).

Maybe remove the wires off of the alternator.

Check the voltage again tomorrow (cold).

The Medic
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Tuesday, March 31st, 2020 AT 4:12 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 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

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Tuesday, March 31st, 2020 AT 4:36 PM
Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,005 POSTS
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
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Tuesday, March 31st, 2020 AT 5:25 PM

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