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Unread 10-13-2011, 09:59 AM   #1
A-Barr
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Help. New alternator new battery not holding charge

'95 2.5 started loosing charge so I took it to parts store to recharge, no good, bought a new one. A couple days later on my way from work midnight power goes down, car dies, no restart, pop tows me home. Next day I replace alternator, replace battery, turn key, nothing. Jump start, batterys still weak. Return battery, buy new starter, good to go. Come to find with new parts, still not holding charge. Help?

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Unread 10-13-2011, 10:04 AM   #2
lukster14
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1995 YJ Wrangler 
 
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did you check what kinda wiring you have and if it is signifigantly degraded? had a ton of issues with my last jeep before I replaced the wiring. also not sure on this, but you checked the grounds right. That seems to be a real common issue too.
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Unread 10-13-2011, 10:07 AM   #3
A-Barr
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Am I looking for all wiring or would this issue be specific to certain ones?
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Unread 10-13-2011, 11:04 AM   #4
Cooter92YJ
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Quote:
Originally Posted by A-Barr View Post
Am I looking for all wiring or would this issue be specific to certain ones?
Your battery cables themselves would be the first to check for any kind of degradation. Look to make sure all connections are clean and shiny. Are the cables even the slightest bit swollen or mis-shapen, indicating corrosion inside the insulation? All connections means positive and negative, which was mentioned earlier. Check where the cable goes into power distribution box too. If your battery is fully charged, does it spark when you hook up the cables? This would indicate something on or shorted.
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Unread 10-13-2011, 11:08 AM   #5
MONSooNmonkey
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If you still haven't tested your alternator I would do that.... before buying a new battery.
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Unread 10-14-2011, 06:10 PM   #6
JWELK
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Sounds as if your alternator isn't. The ECM is the regulator.
With the engine running hold a screwdriver near the back of the alternator. If you have field current the screwdriver should be attracted to the housing. If not, you will need a voltmeter. There are two small wires on the back of the alternator. Both should be approx 12 VDC with the ignition on and no running. With the engine running one should be 12 VDC the other much less. If not either you have corroded wires at the ECM plug, or a defective ECM.
There is another 5 page post covering this with Mistic as the OP.
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Unread 10-14-2011, 09:32 PM   #7
nembudonna
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Check the current draw between the battery with the key off. There may be a current draw with the key off. Something is sucking juice. Try chargeing your battery and then disconnecting your neg cable when you turn your jeep off. Replace it when you want to start it. If it strarts, you have something drawing the current out of the battery.
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Unread 10-14-2011, 10:03 PM   #8
moonshinefuel
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I am wondering if the check engine light ever came on. And what codes is it displaying.
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Unread 10-14-2011, 11:38 PM   #9
Sleuthhound
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I just had an issue today with my battery (which has been plagueing me). I thought my battery wasn't holding a charge. Fired up fine for my way home from work. I tried to leave after I got home - it wouldn't start. After MUCH screwing around, including charging the battery, jump-starting the jeep and letting it run, much voltmeter testing etc, we figured out the negative battery terminal connector was shot and not connecting properly.

We also popped the cables out of the positive terminal connector and they were all oxidized and nasty. After cleaning those thoroughly and jury-rigging the negative terminal connector, we got it running. So I would suggest to check your terminals.
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Unread 10-15-2011, 11:15 AM   #10
moonshinefuel
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At "Pep Boys" , a local parts store, they used to sell Energizer car batteries. Now they dont. They have their own brand, ProStart". I took my energizer battery in after 5 years of good dependability, and went on their pro-rate warrentee and switched to their brand. My first battery lasted 1 month, it would not hold a charge properly, after as little 12 hours, it struggled to turn over my engine. So, I disconnected the terminals, to see if I had a draw. Still, same result battery drained even when not connected. I have since returned it for a new one free of charge, about 3 weeks ago. So far so good. Problem is of course dealing with lesser quality is it can effect other parts, like making my alternator work harder, unnecessary strain on it.
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Unread 10-15-2011, 02:01 PM   #11
kahanabob
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Quote:
Originally Posted by nembudonna View Post
Check the current draw between the battery with the key off. There may be a current draw with the key off. Something is sucking juice. Try chargeing your battery and then disconnecting your neg cable when you turn your jeep off. Replace it when you want to start it. If it strarts, you have something drawing the current out of the battery.
i would do as stated above........something might draining it?
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Unread 10-16-2011, 01:12 AM   #12
A-Barr
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Dealer dagnosis says my PCM is shot and hence busting each alternator I'm putting in it. 40 and 50 fuses blown also. My engine codes were batt undercharge, AC(which I don't have) and batt unplugged.
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Unread 10-16-2011, 02:26 AM   #13
jsawduste
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Quote:
Originally Posted by A-Barr View Post
Dealer dagnosis says my PCM is shot and hence busting each alternator I'm putting in it. 40 and 50 fuses blown also. My engine codes were batt undercharge, AC(which I don't have) and batt unplugged.
A bad ECM (it`s not a PCM) would not cause 40 and 50 amp fuses to blow.

A short in the wiring would cause the fuses to blow. A short to the field circuit of the alt. would make the ECM field circuit fail. Which would cause a no charge situation.


Wiring is not that hard. Get yourself a wiring diagram. Start at the alt and follow each wire. There is only 4 wires.

Ground cable
Charge cable to battery
Field wire to ECM..........On mine it is Tan in color
12 volt reference that splices and goes to the Coil and PDC..........Green on mine.

If the wire or connection is other then clean and bright it is no good. Any breaks in the insulation or melting is not acceptable. Whatever your problem is you WILL find it if it is bad enough to blow a 50 amp fuse.
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Unread 10-16-2011, 08:19 AM   #14
JWELK
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Have to agree with Jsawduste on this one. The ECM/PCM with a complete failure in the charging circuit (a ground on pin on pin 20) will only cause the alternator to go to full power. In fact grounding this point is one of the tests that are suggested to "test" an alternator. Which fuses are blowing? The wiring is straightforward and relatively easy to access.

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Unread 10-17-2011, 09:35 AM   #15
A-Barr
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Thanks for the advice. I haven't had a chance to take a look at it due to work but I'm definitely giving it a try over spending $800+. Any more comments suggestions and ideas are helpful and appreciated
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