Alternator issues.....

[dodgedarren]

I have been having a charging system issue.
Sometime the it charges and sometime it don't.
NOw I believe I shorted something out when I was checking
the system with the volt meter.

1. Alternator only putting out 12v

2. Car wont run when I disconnect the battery.

3. How can I test the voltage regulator ?

[Bowers]

Having the exact same issue. Need to know how to do #3

[Pete in NH]

Up to and including 1969, Chrysler  used an electromechanical voltage regulator and a single field wire alternator. From 1970 on up they used a two field wire alternator and electronic regulator. Many earlier cars were converted to the newer electronic system and it would help to know which system is on the car to tell you how to check the voltage regulator. The check out procedure is different  for the two systems.

The old system has an alternator with two wires coming from it, one heavy black wire on the output stud and on lighter gauge green wire to a field terminal. The electronic system has two field wires, one green and one blue in addition to the heavy black output wire.

[Bowers]

Mine personally is a 1970 with two field wires plus the live wire. The volt Meter reads 12 and doesn't go up to 14. Changed the alternator to a new one and the same thing.

[Pete in NH]

Okay, on a 1970, first check if you have 12 volts on the blue field wire of the alternator with the ignition switch in the run position. Next, disconnect the connector at the regulator and check for 12 volts on the connector pin with the blue wire, again, with the ignition switch in the run position. If these two checks are okay, with the engine running and the connector still off the regulator, ground the green wire on the connector for an instant and measure the battery voltage while doing so. If the voltage jumps up to 17 or so volts the alternator is good and the regulator likely bad or it has a bad ground. A lot of after market parts these days are not the greatest, so I like to use original Mopar regulators. P/N 4529794 seems to be the current regulator part number.

[Bowers]

Thanks Pete,
I changed out the regulator before I read this post and the same thing happens. Battery still reads 12V with both the old and new alternator.

[Nacho-RT74]

75 amps will never go through ammeter except if batt get discharged ( and still ). You don't need to get worried about that, just about bulkhead terminals

[dodgedarren]

Hi, I converted my 68  to electronic ignition. It has a Large black wire and a small purple wire on the post and a small green wire
on the field terminal.

What should I check?

[Pete in NH]

Bowers,

Did you check for 12 volts on the blue wires and then momentarily ground the green wire at the regulator connector and measure the battery voltage?

Dodgedarren,

Electronic ignition and electronic voltage regulation are not the same thing. From your description it sounds like you still have the old single field wire system. Do you have a voltmeter you can measure the battery voltage with? If so, Do you have battery voltage at the alternator output stud? Next, there should be a blue wire going to the. Do you have 12 volts on it with the ignition key in the run position? voltage regulator on the firewall

[Bowers]

I didn't have a volt meter handy but I did have a test light. The test light showed power in the blue on both connections. I couldn't test the ground wire. Gonna take the alternator in to PartSource tomorrow to be tested. The car is heading to the body shop tomorrow for an overhaul so I told the guy to pull the engine and we'll have a look at the wiring. The ignition switch stopped working also. Just changed the neutral safety switch last month. Not sure what is going on.

Thanks.

[Bowers]

Replaced the alternator and regulator to new parts and am now charging just fine.

Thanks

[dodgedarren]

Bowers,

Did you check for 12 volts on the blue wires and then momentarily ground the green wire at the regulator connector and measure the battery voltage?

Dodgedarren,

Electronic ignition and electronic voltage regulation are not the same thing. From your description it sounds like you still have the old single field wire system. Do you have a voltmeter you can measure the battery voltage with? If so, Do you have battery voltage at the alternator output stud? Next, there should be a blue wire going to the. Do you have 12 volts on it with the ignition key in the run position? voltage regulator on the firewall

Hey Pete,

I had the alternator bench tested and it is fine. Changed voltage regulator and still having issue that is periodic.
when is is not working:

Amp gage in car is about -20 with the key in the start position and no readable voltage to the stud on the alternator.

[Pete in NH]

If you don't see the battery voltage at the alternator output stud you have an open circuit in the wiring. Since your ammeter swings negative, I suspect the open is somewhere along the heavy 12 gauge black wire the runs from the alternator output stud through the bulk head connector pin to what Chrysler called a "splice joint". This is one  side of the ammeter and feeds all the electrical loads in the car. Follow that heavy black wire and look for an intermittent connection. My money would be on the bulk head connector pin being burnt or corroded but, it could be anything along that wiring. 

[dodgedarren]

You nailed it. Bulk head pin is fried. So with the car NOT running put the key in the run position I should get a voltage reading from the stud on the alternator??? Also How ban I repair the pin with out replacing the bulk head on the fire wall?

[Pete in NH]

You should see 12 volts on the alternator output stud all the time , even with the key in the off position. Whether or not you can repair the present bulk head pin position that is fried depends on how bad it is. If the plastic connector housing is melted up on either side of the connector you may have to replace them. The pins themselves can be replaced and are called Packard 56 types. You may be able to find them at you local NAPA store and they are available from on line sources. I would replace the pins on both sides of the connection.

The best long term solution to this problem is to install what the factory called the "fleet bypass" modification. This was done on cars carrying 60 amp alternators. You run a new #8 gauge black wire from the alternator output stud through a hole in the firewall lined with a rubber grommet directly to the back of the ammeter. You then run a second new #8 gauge red wire from the other side of the ammeter through the same firewall hole directly to the 5/16" battery stud on the starter relay. This removes those troublesome bulk head connectors pins from the high current circuit path.

[myk]

Thank the heavens for Pete's expertise...

[grizparker]

Does it matter which side of the ammeter the wires are connected?  Is there a positive and negative side?

[nascarxx29]

for gauge to read right the polarity is marked on the dash frame where it says red

[69wannabe]

Thank the heavens for Pete's expertise...

Amen!!!