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Bought my '01 Cherokee back in March & have had nothing but problems since; I've been slowly fixing them when I have the time/cash. However, this particular issue has me stumped (and it's happened twice now).

Today, I was driving along when my check gauges light came on and my battery gauge plummeted to 0. My windows, windshield wipers, blinkers, etc; all electronics were incredibly sluggish. I was able to limp-it back home and start some troubleshooting. Tried to start it up & it kept acting as though it needed a jump. This actually happened before, but I was able to tighten the cables on the terminals and wiggle the wires a bit to get everything to work properly again. Having had this problem before and thinking it didn't just "need a jump": first, I replaced my battery cables as the old ones were corroded, I had to splice some stuff because I couldn't afford the factory replacements; I don't believe that is the issue, though.

Still nothing.

Next, I lugged my battery up to Advanced Auto, did a check and ended up having to replace it, too. BAM! Started up like nobody's business. This victory was short lived, though. After a single minute of driving: "Check Gauges" lights up & battery shows as 0.

Now that this has happened a second time and having replaced the cables AND replaced the battery, I am at a loss of what to do next.

I'm thinking of taking it in somewhere, but I'd really like to see if I can find & fix this problem myself first.

Any suggestions would be appreciated.

//UPDATE

After testing the battery (per Larry's suggestion), I have a few more details.

  • The battery is putting out plenty of volts on it's own with engine off.
  • Before the light comes on and the gauge falls to 0, my battery gauge hovers at 12; meaning, the needle will move to just before or just after the 12V hash line intermittently
  • The Check Gauges light will only come on after it's hit third gear and has been running in it for a least 10 seconds. I tested this for about 5 minutes riding around my neighborhood in 1st and 2nd trying to keep it under 3rd. Once I hit the main streets, the light came on within 10-15 seconds. I tried this twice.
  • After checking with a DVOM while the light is on, the voltage is right around 12V.
  • After that, I restarted and checked it while idling (no driving first, light off): same voltage.

What should be my next step? Thanks!

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    Based on the new information you have added, the alternator is not charging. You can confirm this by taking the vehicle to a local parts store and have them test the alternator for you. This is done with the alternator still on the car. This vehicle has an external voltage regulator so that could also be the problem. The parts store may not be able to tell which one is bad without taking the alternator off of the vehicle. My money is on the voltage regulator based on what you have described
    – Move More Comments Link To Top
    Commented Jun 29, 2011 at 14:35
  • Checked my alternator at Advanced Auto: it's getting no charge at all! o.O Guy said to check my wiring on the back of the alternator for corrosion, lose connections, bad/frayed wires. Also, I need to check the ground from the negative to be sure it's got a good connection. Any other ideas?
    – joshmax
    Commented Jun 29, 2011 at 19:46
  • Forgot this: my alternator usually makes a high pitched whine while running and increases in pitch when you press the accelerator. The past few days, I have not been hearing it. Today, it randomly started doing it again: my battery gauge is back up to 13 or 14V. Had Advanced Auto do another check & everything came back as normal. I'm assuming my alternator or some part of it, is wearing out & has not been working at all the past few day :/ I'm going to purchase a new one, replace it & update afterwards. Thanks.
    – joshmax
    Commented Jun 30, 2011 at 23:54
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    I strongly disagree This sounds more like a bad connection between the voltage regulator and the alternator or a bad voltage regulator. If you decide to take the alternator off anyway have advance test it off the car before you replace it.
    – Move More Comments Link To Top
    Commented Jul 1, 2011 at 3:50
  • Thanks for the feedback. I already bought one :( Anyway, even if it were just a bad connection or a bad regulator all together, I still have the problem of my alternator whining. AND, it's getting increasingly louder since March. When it finally came back on yesterday, it was incredibly loud. Guys at AutoZone said whining means bad bearings and if it's been happening for a while, it most likely will quit on me soon. I think I'd rather replace it, have a warranty & be done with it. I'll have them check it once it's off, though, just to be sure. Will let you know how it goes. Thanks again!
    – joshmax
    Commented Jul 1, 2011 at 15:01

2 Answers 2

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If you have a DVOM (digital volt ohm meter) check the voltage of the battery when this is happening. I suspect that the alternator is not charging. The voltage with the engine running should be (roughly) between 13 - 14 volts, anything less than 12.6 means the alternator is not charging.

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  • Thanks, I will check tomorrow & report. If the alternator is not charging, could this mean my alternator is going out?
    – joshmax
    Commented Jun 29, 2011 at 5:12
  • Yes, but you will need to check it when the problem is happening.
    – Move More Comments Link To Top
    Commented Jun 29, 2011 at 5:22
  • I've updated the question with what I found out. Thanks for the help so far!
    – joshmax
    Commented Jun 29, 2011 at 13:31
  • I appreciate the help. I replaced the alternator & checked the old one at Advanced: it was dead in the water. Thanks again! I'd up-vote your answer but I don't have that privilege yet :D
    – joshmax
    Commented Jul 2, 2011 at 20:19
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My jeep has problems with the altinator as well and seen this thread notice that my jeep has the same simptoms and though id jump in here.my battery guage drops when I rev the motor to about 2200 rpm then it dies .its doesn't always do it but I've spent well over 400 getting it toed back to the house.I only paid like 300 bucks for it so I'm not doin to bad I got like a grand in it and its only got 50,000miles on it.but my altinator doesn't whine?

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    What are the flaws to upgradeing to a high output altinator?
    – james
    Commented May 4, 2012 at 15:17

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