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alternator???


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buckhunter069
User

Aug 15, 2014, 6:46 AM

Post #1 of 7 (1074 views)
alternator??? Sign In

alright gentlemen, im needing some advice. 2004 jeep Cherokee, 4.7L, 160000 miles.


about 2 weeks ago, while driving, I noticed the gage for my battery was dropping fast. I was able to make it where I was heading, and put it on a charger. when I returned home later, I removed the alternator. I had it tested at "the zone". it passed. I made him test it 3 times, even thought I could tell he was not excited about it. I returned home, installed the same alternator, cleaned up and lubed all connections from alternator to battery and such. suddenly, the alternator was charging the battery. drove it for a week and saw no issues. then yesterday, it did it again. I must note that I just replaced the battery in march with a brand new one from farm n fleet.
I have removed the belt again this morning. I noticed now that the pulley on the power steering pump does not turn freely in both directions. not sure if this is what it is supposed to do, just a thought. could the alternator have tested just fine then, but still be bad. should I test it again, or are there other areas I should look at first?


another possibly important note is that while I was driving, and watching the gage, the volts would drop to around 9. however, sometimes, and only sometimes, if I would turn on the AC full blast, then the gage would jump to 13.5, and start charging. any ideas???


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Aug 15, 2014, 7:38 AM

Post #2 of 7 (1068 views)
Re: alternator??? Sign In

Near certain this alternator is regulated to charge thru computer NOT from inside it so testing can show good out of the vehicle.


In that cleaning up connections and just the course and bumping around a bit of taking it out snapped it to working for a while then later quit but asking it to work harder later came back to working could make being sure of a fix tricky.


Do you know if this is an original alternator to this vehicle OR plenty of miles on it? IDK why but some the plain brushes inside get weak contact with wear and can be intermittent like that.


Getting old but some (any with that behavior) sometimes if you caught it while not charging and tapped on alternator while running safely and that snaps it to working it's still not 100% but seems alternator is at fault. You can (usually) get new brushes and buy some time if you have the gumption to take an alternator apart or if rechecking any wiring to it involved even the wiggle test of plugs and wiring to it you are convinced is now OK go for another alternator.


Things that are intermittent without a problem staring at you there is some risk that replacement is NOT the problem and we as techs don't like that way of working/fixing things.


Certainly I hope you are aware you only have so long to drive without alternator charging so keep that in mind if it stays not charging to get to where you can deal with it as it will stop running.


PS pulley only turning one way? Sorry - just not sure on that but a bit surprised but doubt the charging issue if anything about that at all,


T



Hammer Time
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Aug 15, 2014, 7:47 AM

Post #3 of 7 (1064 views)
Re: alternator??? Sign In

As Tom pointed out, this system is regulated by the PCM and the system must be tested in the vehicle.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



buckhunter069
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Aug 15, 2014, 8:31 AM

Post #4 of 7 (1062 views)
Re: alternator??? Sign In

okay, let me know if this means anything. I mentioned that the AC would sometimes trigger the alternator to charge. well, I happened to have a can of R134a with conditioners. I started it up and charged the AC. watched it run for about 5 minutes with the AC cranked. I watched the clutch engage/disengage on the AC repeatedly. when it would engage, the alternator would charge. shouldn't the clutch remain spinning on the AC pump the entire time its on. didn't seem like it was normal. gotta admit, ive never paid attention to the way the AC pump should work.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 15, 2014, 8:42 AM

Post #5 of 7 (1058 views)
Re: alternator??? Sign In

Wow, that is odd. The field wire must be finding ground through the compressor clutch somehow. That's going to take some investigating.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



buckhunter069
User

Aug 15, 2014, 8:54 AM

Post #6 of 7 (1055 views)
Re: alternator??? Sign In

what exactly does that mean HT? you wouldn't lean toward the AC clutch being a problem? like I said, not sure how it is supposed to work. if it were seizing, wouldn't this present resistance and perhaps not turn the alternator fast enough, preventing it from charging properly?


GC
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GC profile image

Aug 15, 2014, 9:06 AM

Post #7 of 7 (1050 views)
Re: alternator??? Sign In

You said it would charge when the compressor clutch was engaged, so wouldnt think that the compressor is dragging it down, or it would be the opposite. The compressor may cycle on/off more often when you have an issue with the a/c (like an unknown charge from a can) HT is referring to the field wire (which is used to regulate the output of alternator) somehow finding ground through the circuit that controls the a/c clutch. Its going to take some testing to figure out what exactly is happening.


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Willing to help, willing to learn... Rob

(This post was edited by GC on Aug 15, 2014, 9:12 AM)






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