doing some tests and with the key on i have 11.87 volts at both field wires the output should be considerably lower on one or am i wrong .
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70 duster not charging .
- Thread starter jimjimjimmy
- Start date
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Jim Jim Jim...
Need a lot of background info
Need a lot of background info
- Isolated field alternator?
- Electronic voltage regulator?
- How are you measuring the voltage. ( From what point to what point)
Engine running or not
engine not running key on
67Dart273
Well-Known Member
Remove green field wire at alternator. Take jumper and ground that alternator field terminal. Start and see if it charges. if not, leave jumper in place, key in "run" and chek voltage at blue wire field terminal, all wiring in place
If you have that voltage and it will not charge, rerun test and with engine running fast, check voltage at alternator output terminal. If it is still low, 12v or less, it is not charging. If it is quite high, way over 14, and not charging, you have a break in the charging line to battery
Other:
VR controls "the amount of ground" of the field via the green wire. Check wiring for function, and make absolutely certain VR is grounded.
So Vr gets switched 12V from key, as does the blue at the alternator field. The VR controls the grounding on the green thus conpleting the field and controlling it.
VR MUST be grounded.
If you have that voltage and it will not charge, rerun test and with engine running fast, check voltage at alternator output terminal. If it is still low, 12v or less, it is not charging. If it is quite high, way over 14, and not charging, you have a break in the charging line to battery
Other:
VR controls "the amount of ground" of the field via the green wire. Check wiring for function, and make absolutely certain VR is grounded.
So Vr gets switched 12V from key, as does the blue at the alternator field. The VR controls the grounding on the green thus conpleting the field and controlling it.
VR MUST be grounded.
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i was gonna do that but with 11.87 volts on both field wires with the key on and engine not running made me think it may not be a good idea
MOPAROFFICIAL
Oogliboogli
Hmm Diode short/grounding ?
i was thinking something like that . i worked normal last fall when i put it away but yesterday when i took her out it wasn't charging .
MOPAROFFICIAL
Oogliboogli
If it doesn't go full charge when you full field the alternator , then yeah it's toast.
If it does full charge then your regulator is bad or not grounded properly. Like he said
If it does full charge then your regulator is bad or not grounded properly. Like he said
On a isolated field alternator the field coil gets its ground (green wire) from the voltage regulator.
The blue wire should be at or near battery voltage.
The fields coil will show + voltage on both sides, If the green wire is disconnected from the terminal on the alt
Do as 67dart273 said, then start and check bat charging voltage. It might be up near 18v so don't run it that way very long.
The blue wire should be at or near battery voltage.
The fields coil will show + voltage on both sides, If the green wire is disconnected from the terminal on the alt
Do as 67dart273 said, then start and check bat charging voltage. It might be up near 18v so don't run it that way very long.
ok grounded the field and its charging so it must be the regulator . with the key on what voltage should there be at voltage regulator plug both terminals ???
One should get battery voltage, the other makes the ground for the field so who knows!
Is the regulator properly grounded, if not that could be your problem
yes .
all tests point to the regulator thanks .
Relativity cheap and easy to swap.
67Dart273
Well-Known Member
Anything in the engine bay switched by the key should be right at battery. Otherwise you have voltage drop. but that close to 12 should not stop it from charging, if VR and alternator are good.
I've posted this before. The "usual suspects" are the ammeter wires and the ign "run" wire going through the bulkhead connector (so at least 3 terminals possible) as well as the key switch connector and the switch itself.
and what year is your car? Newer models, 72? 73? have an annoying white connector where the engine harness goes to the firewall. Those are a known problem. Cut it out of there, and permanently splice the wiring together.
Otherwise, consider a relay to "fix" the problem. Locate and cut your "run" wire coming out of the bulkhead connector. Feed the firewall end to trigger a bosch relay, and connect the engine bay cut end to the switched contact. Feed the relay contacts with about a no12 fused or breakered, from the start relay "big stud."
Doing this ALSO fixes "over charge" (overvoltage) caused by harness voltage drop
I've posted this before. The "usual suspects" are the ammeter wires and the ign "run" wire going through the bulkhead connector (so at least 3 terminals possible) as well as the key switch connector and the switch itself.
and what year is your car? Newer models, 72? 73? have an annoying white connector where the engine harness goes to the firewall. Those are a known problem. Cut it out of there, and permanently splice the wiring together.
Otherwise, consider a relay to "fix" the problem. Locate and cut your "run" wire coming out of the bulkhead connector. Feed the firewall end to trigger a bosch relay, and connect the engine bay cut end to the switched contact. Feed the relay contacts with about a no12 fused or breakered, from the start relay "big stud."
Doing this ALSO fixes "over charge" (overvoltage) caused by harness voltage drop
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