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Old Jun 14, 2012 | 12:37 AM
  #1  
stev-o's Avatar
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From: phoenix az
Year: 1989
Model: Cherokee
Engine: 4.0l 6 cylinder
Default alternator...

my alternator must be getting week because wen the head lights are on and the ac it draws alot of power that the dash gauge drops from 14v to like 10v

are my headlights stuck on high because the headlight light on the dash is on wen there on

whats the easiest way to replace the alt
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Old Jun 14, 2012 | 12:54 AM
  #2  
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Year: 1988
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First, you need to verify that it's an alternator problem, and not something else.

I've posted a writeup on primary electrical testing, search it up and run through it. Fifteen to twenty minutes that can be quite illustrative...
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Old Jun 14, 2012 | 01:03 AM
  #3  
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Mine does the same thing, the renix has some voltage and ground issues.
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Old Jun 14, 2012 | 01:32 AM
  #4  
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Year: 1988
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Originally Posted by stev-o
my alternator must be getting week because wen the head lights are on and the ac it draws alot of power that the dash gauge drops from 14v to like 10v

are my headlights stuck on high because the headlight light on the dash is on wen there on

whats the easiest way to replace the alt
Check the belts too. If the alternator belt is loose then it wont make as much power as it is supposed to. But yes, our jeeps are smart and start to draw power from acc like lights and stereo to reroute power to keep the motor running. Check grounds and such and take the alternator into Autozone or somewhere else to get it tested before you spend the money on a new one.
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Old Jun 14, 2012 | 01:36 AM
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Year: 1987
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You can test your alternator yourself with a multi meter
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Old Jun 14, 2012 | 07:24 AM
  #6  
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Originally Posted by cdf43
You can test your alternator yourself with a multi meter
See my previous post. Then, dig out the writeup. I got tired of typing it up - I did a copypasta and posted the exact same writeup on six or seven boards - including this one. It's a simple procedure, and can be done in short order.

And it's more illustrative than most parts house tests can be.
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Old Jun 15, 2012 | 08:08 AM
  #7  
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Originally Posted by 5-90
See my previous post. Then, dig out the writeup. I got tired of typing it up - I did a copypasta and posted the exact same writeup on six or seven boards - including this one. It's a simple procedure, and can be done in short order.

And it's more illustrative than most parts house tests can be.
Here is a copypasta of 5-90's write-up

https://www.cherokeeforum.com/f2/bat...or-test-78125/
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Old Jun 27, 2012 | 06:00 PM
  #8  
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From: phoenix az
Year: 1989
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So I put a new alt in and it's the same thing happens
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Old Jun 27, 2012 | 06:02 PM
  #9  
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Originally Posted by stev-o
So I put a new alt in and it's the same thing happens
When I turn the headlights on the gauge on the dash drops from almost 14 to like 10
Same if I have ac on how
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Old Jun 27, 2012 | 06:11 PM
  #10  
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........ Which is why people suggested you test it before you replace it to avoid wasting money on an unnecessary new part.

Sounds like you may need to do some ground cleaning. You have a Renix and it is extremely important that your grounds are fresh as can be
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Old Jun 27, 2012 | 06:12 PM
  #11  
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Hey Steve, does that Alt output wire go right to the starter relay? I really don't know, thought you might.
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Old Jun 27, 2012 | 06:14 PM
  #12  
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From: Mercer County, NJ
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Yes grounds clean, battery terminals clean and another important part all wiring tight under clamps too. This happens alot to alot of us here
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Old Jun 27, 2012 | 06:47 PM
  #13  
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Where are some of the grounds i should clean up
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Old Jun 27, 2012 | 07:18 PM
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Have you checked your battery cables? check those too. If you can see the copper strands see if it's tarnished/corroded. I experienced the same problems so I just decided to change my battery cables just cuz I have 2 gauge amp wires laying around. It fixed my issues and with further looking into the cables, I found that the inside was corroded.
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Old Jun 27, 2012 | 07:37 PM
  #15  
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From: Mercer County, NJ
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Originally Posted by USMCgunrock
Have you checked your battery cables? check those too. If you can see the copper strands see if it's tarnished/corroded. I experienced the same problems so I just decided to change my battery cables just cuz I have 2 gauge amp wires laying around. It fixed my issues and with further looking into the cables, I found that the inside was corroded.
This was part of my issue, battery stopped charging well and thought it was my alt. did some looking into her and fix up the cables and everything was good afterwards
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