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Old 01-26-2008, 12:31 PM   #1
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Alternator output?

My Optima redtop died a couple months ago so I got a new battery. The new one just died
My volt gauge has been running a little over 14 but I didn't think too much about it since the battery wasn't showing any signs of over charge before it died.
Stuck a meter on it and it's running at 14.7 volts, think I should replace the alternator?
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Old 01-26-2008, 02:16 PM   #2
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No thats not that high......13.5-14.2 would be considered normal.......14.7 is on the high end of the normal scale but not off the scale.......Ive seen alot of dud batteries in the last couple years for whatever reason.....g

Move along ...nothing ta see here

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Old 01-26-2008, 04:22 PM   #3
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Not sure on the TJ's but on my XJ I have a battery sensor that controls the PCM which controls the amount the battery is charged. It is under the battery tray. Your battery charging is not controlled by the alternator anymore, it is controlled by the PCM which on the XJ is on drivers side behind the headlight. I know the TJ has one too but it's just too dam could out there to go pop the hood and look for it and I don't remember where it is off hand. If the PCM is bad it could overcharge your battery, what you need to do is use a DVM and a needle probe on that line in the back of the alternator then watch it as it turns on and off.
I just had to do an alt on my 98 XJ, and a NDenso and that puppy was expensive, I'm not used to paying more than $60 for an alternator but then it's been over 15 years since I bought or needed one.
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Old 01-26-2008, 06:34 PM   #4
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If the alternator goes out its usually not putting anything out, if its over charging its the regulator which is built into the PCM. I'm thinking you got a bad battery.
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Old 10-19-2009, 09:31 PM   #5
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re jeep pcm

Hi my buddy has a 2000 wrangler sport which he just replaced the pcm. THe pcm came out of an automatic jeep and he has a manual. HE needs to flash the pcm right? Im trying to find a thread on how to do it. any input wold be appreciated. oh the battery wont hold a charge as a result of the this.
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Old 10-19-2009, 09:39 PM   #6
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A Opima must be loaded with 14.7V. 14.2-14.4 is also ok but then it is only 95-97% full.

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