1970PAValiant
master of the break down
So I lost all charging from my alternator while driving home. was wondering where I should start looking for the problem
lost alt.
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67Dart273
Well-Known Member
Identify the green and blue field wires on the push on terminals at the alternator
With key on, probe the blue and see if it's hot. If so, put it back on the alternator and probe the alternator push on terminal where you removed the green. That is the alternator terminal, not the wire. It should now be hot.
Now take a clip lead and GROUND the exposed push on terminal ON the alternator.
This will apply "full field" current. Start the car and gently bring up RPM. the ammeter should go up more and more. Don't wind it way up because the voltage will be going up, too
If this all checks out, you have a regulator/ regulator wiring problem.
If it does NOT charge, Put your lamp/ voltmeter on the output stud with the clip lead still attached. Gently rev the engine If the meter goes up or the light gets brighter, you have a wiring problem in the man output wire, probably the bulkhead connector or ammeter circuit wiring.
With key on, probe the blue and see if it's hot. If so, put it back on the alternator and probe the alternator push on terminal where you removed the green. That is the alternator terminal, not the wire. It should now be hot.
Now take a clip lead and GROUND the exposed push on terminal ON the alternator.
This will apply "full field" current. Start the car and gently bring up RPM. the ammeter should go up more and more. Don't wind it way up because the voltage will be going up, too
If this all checks out, you have a regulator/ regulator wiring problem.
If it does NOT charge, Put your lamp/ voltmeter on the output stud with the clip lead still attached. Gently rev the engine If the meter goes up or the light gets brighter, you have a wiring problem in the man output wire, probably the bulkhead connector or ammeter circuit wiring.
1970PAValiant
master of the break down
ok thanks so much I'll get to it in the next 2 days
1970PAValiant
master of the break down
I checked everything, my master cylinder was slightly leaking and got fluid on my voltage reg wires shorting it out
1970PAValiant
master of the break down
it died again today, started to check the wires, the green wire has 12v when the key is turned on. where does that wire goto?
67Dart273
Well-Known Member
If you checked the green WIRE disconnected at the alternator, that wire controls the GROUND on the field of the alternator to control charging.
That is why I told you to try clipping the alternator terminal which the green came off of to ground and check for charging. By doing this you are checking:
That the blue (other) field wire is supplying 12V from the ignition circuit
that the alternator is good and can work
that the big black charging wire is continuous back to the battery.
another problem is that you may have worn brushes, or gotten oil slung into the alternator and "oiled up" the brushes.
That is why I told you to try clipping the alternator terminal which the green came off of to ground and check for charging. By doing this you are checking:
That the blue (other) field wire is supplying 12V from the ignition circuit
that the alternator is good and can work
that the big black charging wire is continuous back to the battery.
another problem is that you may have worn brushes, or gotten oil slung into the alternator and "oiled up" the brushes.
1970PAValiant
master of the break down
yes I disconned the alternator and grounded it out, the alt came on and when I reved the engine, the ammeter went up. I took off the plug for the volt reg. and checked continuity between the wires, they came out good and I put dielectric grease in it and plugged it back in. Now my alt is always charging or at least the ammeter suggests.
67Dart273
Well-Known Member
I would work the regulator plug in/ out to scrub the terminals clean on both the plug and the regulator, and make SURE the regulator is grounded.
IF it seems to be charging, now is a good time to check the battery with a meter and make SURE that it's charging at the correct voltage.
Get the battery "up" that is normalized after starting, the ammeter should drop off to the middle. Check battery voltage with engine simulating "medium cruise" RPM
Should be 13.8--14.2, not below 13.5 and not above 15
IF it seems to be charging, now is a good time to check the battery with a meter and make SURE that it's charging at the correct voltage.
Get the battery "up" that is normalized after starting, the ammeter should drop off to the middle. Check battery voltage with engine simulating "medium cruise" RPM
Should be 13.8--14.2, not below 13.5 and not above 15
1970PAValiant
master of the break down
alright, will def do that tomorrow. I don't wanna fry my battery. thanks you've been very helpful 
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