voltage drop - JeepForum.com
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post #1 of 5 Old 04-12-2013, 10:08 AM Thread Starter
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1991 YJ Wrangler 
Join Date: Mar 2013
Location: des moines
Posts: 6
voltage drop

i am having a hard time figuring this problem out can anyone help

i have a 91 yj and the problem with it is when i press the gas the battery voltage drops down dramatically. If i were to stay on the gas it would eventually die. when i shift back to neutral the battery voltage goes back to 14. I have tried to find a bad wire and i am not seeing one but i am not sure i have seen them all. what is it that pulls power when press the accelerator.

any ideas would be much appreciated.

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post #2 of 5 Old 04-12-2013, 10:12 AM
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1999 XJ Cherokee 
Join Date: Nov 2012
Location: London
Posts: 220
Sounds like the alternator. When your engine is running it requires power to run everything but mainly spark for your engine. When you press teh pedal the RPMs go up and so does the power required for the spark. The alternator gives consistent power when the engine is running to have enough power to run everything in your Jeep.

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post #3 of 5 Old 04-12-2013, 10:42 AM Thread Starter
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1991 YJ Wrangler 
Join Date: Mar 2013
Location: des moines
Posts: 6
i have had the alternator checked by 2 different shops and they both say it is ok
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post #4 of 5 Old 04-12-2013, 10:53 AM
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1994 YJ Wrangler 
Join Date: Mar 2007
Location: Bham
Posts: 239
check the wiring off the alternator. Especially the ground wire. and the connection points coming off the alternator.
keep us updated. like to see what the issue or fix will be
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post #5 of 5 Old 04-12-2013, 10:55 AM
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1989 YJ Wrangler 
Join Date: Apr 2008
Location: Detroit
Posts: 24,647
Check your big 50 amp fuses in the PDC. It sounds like you have a bad one.

Try reading the voltage with a meter at the battery when you do it. The guages are notoriously bad. If you are thinking that it is a loading condition the only thing that draws more power then at idle is the ignition system itself.
What happens to your voltage if you leave it at idle and turn on all your electrical loads: blower wipers, radio, etc.?
Increase your idle speed and recheck it.

It is very unlikely that you have a loading condition that is changing like that. I would suggest cleaning all the wires and grounds from the battery and the alternator as a first thing.
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