Need some help on charging issues. Coming home last night from the White House after HBO filming with the 65 Valiant I noticed the Amp meter on discharge. Put my meter on the battery when I got home and sure enough, not charging. I've upgraded to the elect. volt. reg. a few years ago and new alternator at that same time. What are the test procedures to determine whether it's a bad voltage regulator or a bad alternator? Thanks.

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64 barracuda
64 valiant convertable
65 valiant sedan
65 signet
74 vw beetle convertable
79 E-250 4WD van
94 dodge dakota

Single field wire alternator? Pull the field wire and ground it momentarily, If it starts charging it's the regulator. If it doesn't it's the alternator. Only ground it for a short time though, it will let the alternator go over 18 volts.

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Official Cookie and Mater Tormentor.

It's dual field alt.

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64 barracuda
64 valiant convertable
65 valiant sedan
65 signet
74 vw beetle convertable
79 E-250 4WD van
94 dodge dakota

…thus burning up the voltage regulator. On a single-field alternator, you do the full-field test by pulling the field wire and using a test lead to connect the alternator's BAT output stud to the alternator's FLD terminal to see if the alternator begins charging.

On the dual-field alternator in question, you pull both field wires, connect one of the alternator's FLD terminal to ground, and connect the alternator's other FLD terminal to the BAT output stud to see if the alternator begins charging. It does not matter which FLD terminal is which.

It's important not to raise the engine speed above idle or system voltage will climb to dangerous levels.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan, will try and let you know results.

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64 barracuda
64 valiant convertable
65 valiant sedan
65 signet
74 vw beetle convertable
79 E-250 4WD van
94 dodge dakota

Dan,
Voltage did not climb so I assume this means bad Alt. and assuming voltage did climb, it would signify bad Volt. Reg?

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64 barracuda
64 valiant convertable
65 valiant sedan
65 signet
74 vw beetle convertable
79 E-250 4WD van
94 dodge dakota

With full field power, the alternator ought to put out as much as it can - which can go to a much higher voltage than you'd like, so turn the radio off before you try that, as I got ~20V when I tried it.

If you get no charging, then the alt is bad - it might just be the brushes (very easy & inexpensive to replace from the outside of a std Mopar alt, unlike other brands). If it's not the brushes, you have to either replace the alt or open it up. It's not unusual for one or more diodes to have failed and the stator windings to be bad. If you do open it up, I'd suggest replacing the bearings too if they're >45 years old. Keep in mind that alternators often partially fail - it's not always all or nothing.

Some parts chains (Pep Boys, Advance Auto) offer free testing of alternators out of the car - sometimes the people there know what they're doing, and sometimes not.

Yeah, be careful where you buy your replacement alternator. The "remanufactured" ones from parts stores are garbage. You can get a new(!) one from Old Car Parts Northwest (or from me; I think I still have one or two new ones on shelf).

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一期一会
Too many people who were born on third base actually believe they've hit a triple.