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Unread 09-30-2005, 01:33 PM   #1
kernalklink
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Voltage Regulator?

I had an issue yesterday driving down the road: My check engine light came on and my battery gauge was clear down by 9 volts. I realize that gauge is an overall output gauge not just a battery, so i didnt make it too far and i was stuck on the side of the road. I went and got a new alternator and a jumpstart and viola the jeep was running again, but the gauge was still around the 9 volt range, i made it about another mile and then back to the shoulder for me. So i went and got a new battery assuming that my battery must have a bad cell or something that wont take a charge. again the gauge was sitting around the 9 volt range so i wheeled to the closest town 2 miles or so and removed the negative cable from the battery and dead was the jeep. I know the cherokees have a external from the alternator, voltage regulator.
Has anyone ever had to change one of these and what was the work like? How much might it cost?

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Unread 09-30-2005, 01:43 PM   #2
Matt Gertsch
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Sounds to me like a cooked battery.
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Unread 09-30-2005, 01:55 PM   #3
kernalklink
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although i did just buy a brand new battery! and have had it hooked up for about 4 minutes.... Also when i unhooked the battery the jeep died? I really doubt it is the battery
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Unread 09-30-2005, 03:25 PM   #4
cmotsvt
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The jeep should die when the battery is disconnected, the computer needs power to run. The voltage regulator is internal to the alternator and is probably nopt the problem. Remove the alternator and have it tested tested at the parts store
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Unread 09-30-2005, 04:38 PM   #5
TheNerd
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Quote:
Originally Posted by cmotsvt
The jeep should die when the battery is disconnected
...I believe that if the engine is running (and the alternator is good and providing charge) you can remove the battery without problems. I have done this before on several different vehicles, admitedly though, not the Jeep.
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Unread 09-30-2005, 07:20 PM   #6
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I thought the jeep would die without the battery, I may be wrong.
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Unread 09-30-2005, 07:28 PM   #7
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the volt gauge runs off of battery voltage. if the battery voltage drops to nine then there is a problem with the charging system. the battery gauge would only drop that low if it was not recieving enough amperage to charge it higher. if the alt is in good running order the jeep will stay running when you disconect the batt if its already running. if when you disconect it it slowly dies out then your alt is not charging. since you got a new alt already and the voltage reg is internal in the alt you have anothet type of problem. the amperage is not getting from the post on the alt to the battery. trace the line and make sure there isnt a fusable link open and make sure the wire itself is connected to all terminals it should be. also check your fuses. i cant remeber if there is a charging fuse in the cherokees. alot of other vehicles have them. next hook a fluke meter up to ground and the term on the back of the alt. get the jeep to run either witha a jump or new batt and make sure the alt is putting out at least 12.5-13 volts. its deffinetly sounds like your charging system isnt getting the power from the alt to your battery. its a very simple system and youve replaced all the main parts already. its going to be somthing else you need to find
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Unread 09-30-2005, 08:52 PM   #8
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It's not your fault but it sounds as if you fell victim to the classic alternator/battery mistake....
First you notice a severe low voltage problem. You change the alternator first. The problem still occurs. You replace the battery second. The problem still exists. Here's a possible explanation:
Bad battery causes failure of a diode in the bridge rectifier in the alternator. After replacing the alternator the battery is still bad and the new bridge diode bites it. You replace the battery and still see a low voltage under running load.

Check the alternator. If it checks out, the likely problem is a system short which most commonly occurs near the starter or coil.

Note to all: if you have concerns about battery/ electrical. Use a multimeter on the battery first. If the battery has less than 10.4 volts with the engine off, don't try to charge it with the alternator. Remove it from the vehicle and deep charge it with a charger. If the voltage of the battery shows 12.2V +/- 15% you should be OK. Start the engine and check the battery voltage with a multimeter again. you should see 14V +/- 1V. If you are showing a value less than before, your alternator should be removed and tested in a shop.
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Unread 01-04-2007, 03:31 PM   #9
KEVMOXJ
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actually it is an external regulated alternator
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Unread 01-04-2007, 03:58 PM   #10
bee guz
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voltage

i am not sure about, the cherokee, but the YJ has an regulator in the control module, and is not servicable.

Check you application, see if it is in the alt or the ecm. My YJ had the same problem and it was the alternator, but it did get a low charge rate, at times, It was due to bad engine grounds, and a dirty corrosion on the back of the guage.

A long time ago it was a practice to check if the alt was bad by pulling off the battery cable why the engine was running, if the engine died the alt was not charging, but today they caution about doing this on vehicles with computers, youare better of useing a small hand held meter.

Check the alt maxie fuses in the fuse block by the battery, that say charging system....
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Unread 01-04-2007, 04:00 PM   #11
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Quote:
Originally Posted by bee guz
i am not sure about, the cherokee, but the YJ has an regulator in the control module, and is not servicable.

Check you application, see if it is in the alt or the ecm. My YJ had the same problem and it was the alternator, but it did get a low charge rate, at times, It was due to bad engine grounds, and a dirty corrosion on the back of the guage.

A long time ago it was a practice to check if the alt was bad by pulling off the battery cable why the engine was running, if the engine died the alt was not charging, but today they caution about doing this on vehicles with computers, youare better of useing a small hand held meter.

Check the alt maxie fuses in the fuse block by the battery, that say charging system....

X2

the ECM controls the voltage and is unservicable...aside from replacing it....
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Unread 01-04-2007, 06:47 PM   #12
Jeds Sr.
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Quote:
Originally Posted by XJH-007
X2

the ECM controls the voltage and is unservicable...aside from replacing it....

Correct, the alternator does NOT have a built in voltage regulator. If it turns out that your ECM is bad, don't spend $$$ for a replacement. Add a $15 external voltage regulator. Other auto's, such as Dodge have this same problem, the ECM goes bad and the alternator won't charge. So what do the local mechanics do?? They don't go spend $250 on a new ECM, they add an external voltage regulator.

They are easy to hook up, check this link.
http://www.jeepforum.com/forum/showt...=1#post2950554
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Unread 09-16-2014, 09:44 AM   #13
wyattx
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I had this problem one time, where the voltage gauge was all the way down. when I turned the car off and turned the key back to the on position the gauge went back to where it is supposed to be. I haven't had a problem with it since, that was about two weeks ago. Last night I was driving home and noticed the check gauges light was on and I look at the voltage gauge and noticed that it was all the way UP. When I started to slow down to a stop the gauge went back to normal position. Any ideas?
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