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Author Topic:   Yet ANOTHER Wiring Question
Boss Hoss
Gearhead

Posts: 223
From: Georgia
Registered: Mar 2001

posted 08-30-2001 05:04 PM     Click Here to See the Profile for Boss Hoss   Click Here to Email Boss Hoss     Edit/Delete Message   Reply w/Quote
OK, this may sound crazy, but here goes: If my battery doesn't seem to be getting charged when the car is running, and I KNOW FOR A FACT that the alternator is good, could the UNDERDASH wiring be at fault? I have replaced ***ALL*** the wiring in the engine compartment, which is BOTH engine compartment harnesses, and I even replaced the little wires to and from the ignition coil!

I have measured the voltage on my battery while the car is running: 12.38 volts, which is the same as when it is NOT running! Also, when I disconnect the battery's negative cable, the car dies INSTANTLY. That tells me that my car is running off of the BATTERY, not the alternator...BUT THE ALTERNATOR IS A BRAND-NEW 65 AMP MODEL! The voltage regulator is also BRAND NEW.

So, I'm wondering if replacing the old wiring harness under the dash is gonna help me somehow. It is the ONLY thing left that hasn't been replaced!!!!!!!!!!!!!!!

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*andy* ([email protected])

also known as...

***Boss Hoss***

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68F100
Gearhead

Posts: 2356
From: Fort Madison, Iowa USA - United We Stand
Registered: Oct 99

posted 08-30-2001 05:46 PM     Click Here to See the Profile for 68F100   Click Here to Email 68F100     Edit/Delete Message   Reply w/Quote
Sounds like you might have gotten a bad alternator. I once had to go through 8 of them to get a good one. The engine should keep running if you disconnect the battery and the alternator is ok (you knew that much already, huh?).

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Boss Hoss
Gearhead

Posts: 223
From: Georgia
Registered: Mar 2001

posted 08-30-2001 07:07 PM     Click Here to See the Profile for Boss Hoss   Click Here to Email Boss Hoss     Edit/Delete Message   Reply w/Quote
68F100:
Would a bad voltage regulator damage the alternator? I had the voltage regulator go bad a few months ago and replaced it. I have had the alternator tested (it tested OK) but I can't remember if I had the alternator tested AFTER I discovered the bad voltage regulator.

One more question: If the alternator WAS bad, wouldn't my "ALT" light come on? (This light is in working condition, by the way.)

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*andy* ([email protected])

also known as...

***Boss Hoss***

[This message has been edited by Boss Hoss (edited 08-30-2001).]

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68F100
Gearhead

Posts: 2356
From: Fort Madison, Iowa USA - United We Stand
Registered: Oct 99

posted 08-30-2001 09:51 PM     Click Here to See the Profile for 68F100   Click Here to Email 68F100     Edit/Delete Message   Reply w/Quote
Someone else will have to tell you about the voltage regulator, cuz I've never messed with them. My ALT light never came on, and it supposedly worked also. I would just run out of juice. Sorry I don't know more, but someone here will.

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franklin
Gearhead

Posts: 131
From: VA
Registered: Nov 2000

posted 08-31-2001 01:31 AM     Click Here to See the Profile for franklin     Edit/Delete Message   Reply w/Quote
The wiring is not too complicated if you go through it step by step. Replacing everything is a good way to fix stuff, but doesn't always work. Lets start by seeing if you have 12 volts to the "I" terminal of the regulator when the key is on. You can check this with a voltmeter or a test light. By the way, this does come from the dash harness. This is the signal to the regulator that you want it to put the alternator "online" so it can charge the battery.

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Boss Hoss
Gearhead

Posts: 223
From: Georgia
Registered: Mar 2001

posted 09-06-2001 11:16 PM     Click Here to See the Profile for Boss Hoss   Click Here to Email Boss Hoss     Edit/Delete Message   Reply w/Quote
franklin:

I finally got around to dragging out my voltmeter and testing the "I" terminal on my voltage regulator...yep, sure enough, it had 12 volts on it with the key in the "ON" position. At this point, the alternator is starting to look more and more like the culprit. One clue: The engine dies IMMEDIATELY when you disconnect the battery while the car's running.

P.S.: And I just installed a brand-new underdash wiring harness...boy, that thing was expen$ive! <:P

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*andy* ([email protected])

also known as...

***Boss Hoss***

[This message has been edited by Boss Hoss (edited 09-06-2001).]

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franklin
Gearhead

Posts: 131
From: VA
Registered: Nov 2000

posted 09-07-2001 01:45 AM     Click Here to See the Profile for franklin     Edit/Delete Message   Reply w/Quote
Ok, the other wiring to check is:
"s" terminal on reg should go to the stator term on alt.

"f" terminal on reg should go to the field on the alt.

"a" terminal on reg should tie into the battery somehow. This is the terminal the reg uses to monitor the system voltage level.

If you think it's the alt, take it to a auto store and see if they will test it for you.

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tech
Journeyman

Posts: 8
From: Lodi Ca. U.S.A.
Registered: Sep 2001

posted 09-07-2001 10:47 PM     Click Here to See the Profile for tech   Click Here to Email tech     Edit/Delete Message   Reply w/Quote
disconnecting the battery with the engine can damage the diode trio in the alt. which will make it not charge correctly

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AKBOSSMAN
Gearhead

Posts: 2912
From: WASILLA , AK USA M&M #743 MCA #40857
Registered: Oct 2000

posted 09-08-2001 01:21 AM     Click Here to See the Profile for AKBOSSMAN   Click Here to Email AKBOSSMAN     Edit/Delete Message   Reply w/Quote
quote:
Originally posted by tech:
disconnecting the battery with the engine can damage the diode trio in the alt. which will make it not charge correctly

oh, Cool!
Note to self, Don't do that any more.

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WAYNE CURTIS
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www.iditarodtrail.com
"If your under control then your not going fast enough" Parnelli Jones

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franklin
Gearhead

Posts: 131
From: VA
Registered: Nov 2000

posted 09-08-2001 12:22 PM     Click Here to See the Profile for franklin     Edit/Delete Message   Reply w/Quote
I agree, I don't like that test. I burnt out an ignition module doing that too.

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Boss Hoss
Gearhead

Posts: 223
From: Georgia
Registered: Mar 2001

posted 09-08-2001 11:02 PM     Click Here to See the Profile for Boss Hoss   Click Here to Email Boss Hoss     Edit/Delete Message   Reply w/Quote
OK, I'm officially an idiot. I must have gotten in a hurry when I re-wired the engine bay, because I inadvertently connected the alternator harness to the starter side of the solenoid instead of the battery side where it belongs. There's no way the alternator could possibly have charged my battery this way! I connected the alternator harness onto the battery side of the solenoid, and now I'm getting a solid 14.10 volts to the battery when the engine is running. DUH! :P

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*andy* ([email protected])

also known as...

***Boss Hoss***

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