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How do i test the voltage regulator in my 69?? I got a brand new battery in my car its a week old and it is about dead. The alternator is good i had it tested.
 

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I think I would just go buy an electronic one and be done. Otherwise, you need to get it to a parts house that can tests the system. (Auto Zone maybe)
 

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Put a voltmeter on the battery with the car off and look for slightly better than 12v. Check while idling and look for between 13v and 14.5v. If that's OK, put the meter on the S terminal of the alt and look for 14v+. It's not as comprehensive as a real regulator tester like the parts stores used to have, but in the 21st century, how many parts store guys have seen a voltage regulator?
 

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Get a digital multi meter and put it on your battery, then start the car. If your car is charging it should read anywhere from 12.8 to about 13.5 volts, maybe a hair more. If the voltage is around 11 or 12 volts Try this :

Pull your regulator plug while the car is still running and jumper the Field wire to your positive terminal. This will "full field" the alternator and your voltage should shoot up. If it does your regulator or wiring has an issue. If not then your alternator has an internal problem.


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I still have my "Full-Fielder" test tool from back in the day.
It would plug into the original socket on the wiring and jump A+ to F. Basically the same as mil1ion described.
Most 'service stations' did this simple process of elimination test back then.
 

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I'm having the exact same issue as well.


Mil1ion said:
Pull your regulator plug while the car is still running and jumper the Field wire to your positive terminal. This will "full field" the alternator and your voltage should shoot up. If it does your regulator or wiring has an issue. If not then your alternator has an internal problem.
And I'll try this tonight as well.
 

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whoa,,, do not pull the plug on the regulator with the car i running, i've been told by an alternator repair shop this can blow out the diodes in the alternator.

the way i was taught was simply hook up a volt meter to the battery with the engine not running to get a baseline voltage reading.
then start the car, if your reading over the baseline 12.8 to 13.5 ish your alternator is charging. if the voltage doesn't go up, and the alternator tested good, then replace the regulator.

i went through 3 new regulators before i found a good one.

the first one caused the lights to flicker all over the car,
the second suddenly began to overcharge the battery
and the 3rd one worked.
 

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Everything stated is essentially correct, but I can clarify a little.

1) engine off, test battery voltage.
2) engine running at 1500 - 2000RPM battery voltage should be at least 1 volt higher than step 1, but not higher than 14.7 volts.
3) If step 2 is ok, then look for a drain on your battery, or the battery itself might be deffective
4) If step 2 is lower than you have a bad alternator or regulator. If step 2 is higher than you have a bad regulator
5) If step 2 was lower full field the alternator by jumping the "A" & "F" terminals in the wire harness that plugs into the voltage regualtor. See pic: http://thelincolnmarkviiclub.org/Gallery/albums/album92/VR_illistrated.sized.jpg The markings "A" & "F" might be different. This is ok, the position is what is important.

6) If full field voltage tested at battery is still not at least 1 volt higher than step 1 alternator is bad. If it is now more than 1 volt higher regulator is bad.




Things to add: unplugging the regulator with the engine running will not harm anything other than discharging the battery.
Disconnecting the battery with the engine running may indeed harm the alternator - do not do this.
 

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Jim Carrol said:
whoa,,, do not pull the plug on the regulator with the car i running, i've been told by an alternator repair shop this can blow out the diodes in the alternator.

Wrong.

Disconnecting a battery cable with the engine running is bad.

The alternator would built up a charge and once reconnected would spike and harm a diode.
 

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removing the regulator plug is NOT disconnecting a battery cable. The battery is still hooked up to the alternator. So there is NO way electrical damage is going to occur to the alternator diodes UNLESS you leave it at full field for a few minutes or so, then heat generated from full fielding may damage something.
 
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