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Unread 07-16-2011, 01:33 PM   #1
airwolf9090
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Voltage regulator

I know the Voltage regulator is in the PCM and i was talking to a buddy who owns a part store and he told me about a guy that had a Voltage regulator problem in his jeep (PCM was his problem) well the guy bought a Voltage regulator for an old chrysler and wired it into the alternator and therefor by-passing the PCM's Voltage regulator all together.... I was wondering if anyone here know how it was done?

Looking online i found this.....
http://store.alternatorparts.com/hd-...rsion-kit.aspx

And i guess doing this will work too?
http://www.cherokeeforum.com/f2/91-c...or-swap-41024/

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Unread 07-16-2011, 06:26 PM   #2
Oldfrog
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Why are you wanting to even do it? Is your alternator not charging?
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Unread 07-16-2011, 06:39 PM   #3
gothchick
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The PCM adjusts the alternator's output based on intake air temp, battery temp, and electrical load. I don't think you can duplicate that functionality with a secondary external voltage regulator.

It could be that your voltage regulation diodes burned out in the alternator itself. If that's the case, there is nothing serviceable inside the alternator and you'll need to replace it as a whole unit.
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Unread 07-16-2011, 07:02 PM   #4
ZeeJay1997
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Quote:
Originally Posted by gothchick View Post
there is nothing serviceable inside the alternator and you'll need to replace it as a whole unit.
I replaced the brushes in mine but it wasn't worth the time it took.
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Unread 07-16-2011, 07:13 PM   #5
airwolf9090
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Well i have went over everything i could today even tried another alternator and its output was the same as the one before.. I even replaced the brushes in the alternator and still the same thing... the regulator is not adjusting the output like it should is my only guess because when i first start it the output is only 13.4V and when i turn on my headlights and foglights, AC and radio the output drops to 12.2V and you can't tell me that is okay i am sick and tired of it dieing at a red light and being to weak to start back up because i played the radio while going to the store.
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Unread 07-16-2011, 09:03 PM   #6
ZeeJay1997
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Have you considered a bad battery?
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Unread 07-16-2011, 09:46 PM   #7
airwolf9090
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Yes i have i had it tested at afew different places and all say its good and it stays strong if i don't run nothing but the engine.
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Unread 07-16-2011, 09:49 PM   #8
ZeeJay1997
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Will it hold 12.6 volts overnight?
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Unread 07-16-2011, 11:07 PM   #9
airwolf9090
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Yes it will.
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Unread 07-17-2011, 06:11 AM   #10
shreksbrother
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I'm currently experiencing the same problem. My battery is fairly new. Battery/alternator repeatedly test good. Mine is maintaining just over 12v, as well. It never drops below, so the alternator is charging, but I can't run my A/C and headlights without listening to the belt whining.

I'm about to change my belt, hoping against hope the belt has stretched over time (it's old and needs to be replaced). Have you checked your belt tension?
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Unread 07-17-2011, 09:47 AM   #11
airwolf9090
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Yep i have my belt is fine.
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Unread 07-17-2011, 09:56 AM   #12
Foundrydude
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I would imagine there's a 1-wire alternator conversion for older chrysler that fits but it becomes a question of if it's a better use of resources than just fixing the PCM.

Most other makes don't factor temp etc into regulating the alternator. They just let the alternator do it's own thing and it does just fine. So from a function standpoint you're not gonna be missing out on much with a non-stock regulator as long as it functions properly.

Good luck!
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Unread 07-17-2011, 09:59 AM   #13
ZeeJay1997
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Quote:
Originally Posted by airwolf9090 View Post
And i guess doing this will work too?
http://www.cherokeeforum.com/f2/91-c...or-swap-41024/
I've read where this has been done with ZJs and worked, but as the links says, the CEL will stay on. If your worried about passing emissions, well you know...
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Unread 07-17-2011, 10:06 AM   #14
gothchick
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Well... Let's think about this.

1) When you turn the key, the alternator light comes on.
2) This tells the PCM to direct power from the battery to the the starter motor.
3) After the engine is started, the PCM then directs the alternator to split it's power output in two directions:

a) Run the engine
b) Charge the battery (The vehicle's subsystems gets 12v supply from the battery even when the engine is running, not directly from the alternator)

If the battery and alternator check out fine, then it seems like maybe the PCM isn't directing the alternator to keep the battery charged, creating an under-charge condition.

I think I'd either take it in to the dealer to have ODBII dignostics run on it, or check the battery temp sensor (and other sensors), or source a new PCM. Heck, you might just have an old fashioned short somewhere. PITA to chase down...
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Unread 07-20-2011, 05:56 AM   #15
shreksbrother
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Hey airwolf, anything further on your issue?
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