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Old 12-05-2012, 03:18 PM   #1
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Alternator/ Charging System Test results

98 wrangler, 4.0-Been intermittently getting a check gauges warning light for a few months and when this happens the voltage gauge in the dash shows zero. Generally, it stays like this until the next time i start the Jeep. Then all appear well. The voltage indicator typically is just below 14 volts.

I had the charging system test at Advance Auto Parts last night and the only concern to the charging system indicated was 'Excessive Ripple' with a RIPPLE value indicated of 465mV and a wave diagram peaking and dipping between -.24V and +.24V. The No Load result was 13.92V & 7.1A. The Loaded result was 13.40V and 7.2A.

I admittedly don't know what any of this means, but the Advanced Auto guy said the fix was to replace the alternator. I want to make sure he's correct cause only time i've ever replaced an alternator was after it was no longer functioning at all and very obvious it had failed. A little bit of reading around the forum and i see the 98 Wranglers voltage is regulated with in the PCM. Can that be ruled out as the problem with this limited information? Is replacing the alternator the right fix? Let me know if I can provide any more information.

Something is in need of fixing, i'm just looking for a bit better degree of certainty i'm fixing the proper things.
Thanks.

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Old 12-06-2012, 12:44 PM   #2
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Anyone?

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Old 12-06-2012, 01:22 PM   #3
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13.8-14.8 is normal, so it appears on the light end of the scale. I'm not an electrics guy, but it seems that checking the cables and connections to ensure maximum continuity would be the first step for me. However, if someone said the brushes and/or windings on my alternator were shot I would have to give consideration to that possibly being the culprit/fix.
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Old 12-06-2012, 02:18 PM   #4
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I am an electrics guy, and it sounds like your alternator either needs new brushes, or just needs to be replaced. I recommend replacing the alternator. Take the air filter box off first - makes access much easier.
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Old 12-10-2012, 01:57 PM   #5
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Thanks, i replaced the alternator yesterday, but in the process of removing the Alternator Harness/PLug from the old to be used with the new, two of the 4 connections that bolt/connect directly to the bottom of the alternator basicly just crumbled from corrosion. Looking for a replacement if anyone has any leads. Chrysler was a dead end.
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