Green and Blue Field Wires

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70 Buster 340

70 Buster 340

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The two terminals on the alt. are both marked 'FLD'.
Question is which wire goes to which terminal?

I have this style alt.
334-2089_Alternate1__ra_p.jpg

and this regulator....
dcc-3690731.jpg

This drawing doesn't help with wire color and the casting doesn't have a + and - .... or a 1 and 2
PC_375__ra_p.jpg
 
Does not matter. What DOES matter is CHECK the alternator that neither field terminal shows continuity to the case/ ground.
 
I'll check to see if one FLD term is Grounded.
So 'Square Backs" came both ways - Floating (un-grounded) and Grounded

Isn't this the circuit I need to follow for a complete rewire of a 70 Duster with a Square Back and the MP regulator?
Duster charge circuit 1.JPG
 
OK checked and neither FLD terminal is common to ground (or BAT)
Measured 63 ohms between the two FLD terminals.

How/where did factory connect the blue/ignition positive wire (from the ballast resistor) to the alternator ?
Then I'll know where to put the green wire....lol :rolleyes:

I can't find any 'documentation' , drawing or casting mark that makes it clear to me.
 
70 Buster 340 said:
I'll check to see if one FLD term is Grounded.
So 'Square Backs" came both ways - Floating (un-grounded) and Grounded

Isn't this the circuit I need to follow for a complete rewire of a 70 Duster with a Square Back and the MP regulator?
View attachment 1715731111
Click to expand...
No they didn't come that way. The aftermarket supplies alternators configured both purposely and accidently in either configuration (also sometimes so they don't work at all).
Your '70 came wired for the isolated field alternator.
See the sticky thread "How to identify Chrysler Alteranators" for how they should be and why 67Dart273 said to check.
 
70 Buster 340 said:
OK checked and neither FLD terminal is common to ground (or BAT)
Measured 63 ohms between the two FLD terminals.

How/where did factory connect the blue/ignition positive wire (from the ballast resistor) to the alternator ?
Then I'll know where to put the green wire....lol :rolleyes:

I can't find any 'documentation' , drawing or casting mark that makes it clear to me.
Click to expand...
Are you upgrading a pre 70 car or what? You have no shop manual?

At some point "not sure physically" the factory just branched off the "IGN1" or "ignition run" feeding the ballast and VR IGN terminal and ran that off as the blue to the field. None of that is fused. Make SURE that VR is grounded, IE scrape some paint around the bolt holes, use star lock washers.
 
the ballast resistor is in the coil circuit and has nothing to do with the alternator. In your drawing it is simply a binding point. Follow the blue wire
from ammeter to ignition switch to the binding point on the ballast to a split; one way powers up the regulator and the other goes to the alternator field.
The other side of the field goes back to the regulator along the green line and the regulator grounds it to cause the alternator to charge. When the reg senses voltage above it's set point, it shuts the charge line off by opening the ground circuit. It does this so fast your damped ammeter cannot see it.
 
70 Buster 340 said:
How/where did factory connect the blue/ignition positive wire (from the ballast resistor) to the alternator ?
Then I'll know where to put the green wire....lol :rolleyes:

I can't find any 'documentation' , drawing or casting mark that makes it clear to me.
Click to expand...
As was stated in post #2 it does not matter. That said, which wire is longer? The Green or Blue and install them accordingly based on distance from the rocker cover..
 
67Dart273 said:
Are you upgrading a pre 70 car or what? You have no shop manual?
Again, 70 Duster... I guess you can call a square back which was in the car and a new wire and MP regulator an up grade.

At some point "not sure physically" the factory just branched off the "IGN1" or "ignition run" feeding the ballast
Yes, found that connection when completely opening up the original harness...see picture below.
and VR IGN terminal and ran that off as the blue to the field. None of that is fused. Make SURE that VR is grounded, IE scrape some paint around the bolt holes, use star lock washers.
Yup, sanded and star washers.
Click to expand...
Before..
Duster wired IMG_1325.jpg

After ...
Duster wire IMG_1363.jpg
 
dadsbee said:
As was stated in post #2 it does not matter. That said, which wire is longer? The Green or Blue and install them accordingly based on distance from the rocker cover..
Click to expand...

Reasonable suggestion but all that was a re-terminated/melted mess and I re-wired. No more wires on the manifold.
 
what-the.......
I don't see any fusible links... you know they need to be air-cooled right, unless you like the possibility of under hood wiring fires. Fusible links are slow-blow self-resetting as good as fool-proof little marvels; but they gotta keep their cool, and if you overload them they simply melt, taking out 5 or so inches of plastic insulation. But if you put them in a conduit alongside other wires, they will take those with them, and that can quickly escalate.
 
IDK if any squarebacks were single field, but the round backs were dual field for only like a year or possibly 2, but were mostly single fields, and it does not matter what field term goes where on a dual field.
 
AJ/FormS said:
what-the.......
I don't see any fusible links... you know they need to be air-cooled right, unless you like the possibility of under hood wiring fires. Fusible links are slow-blow self-resetting as good as fool-proof little marvels; but they gotta keep their cool, and if you overload them they simply melt, taking out 5 or so inches of plastic insulation. But if you put them in a conduit alongside other wires, they will take those with them, and that can quickly escalate.
Click to expand...

Yup, long ago had one melt that black taped into the harness... total mess.

Which circuit and what rating would you recommend being protected by fusable links?

A 10 AWG charge (BAT) wire was used that goes back to the tail panel 4 post master on/off and trunk battery ... does that need a fusable link ?
It didn't appear to have one when the battery was up front.
 
70 Buster 340 said:
Which circuit and what rating would you recommend being protected by fusable links?
Click to expand...
In a factory harness as far as I can tell they were only used to prevent battery short to ground from burning wires.
The typical a-body '65 - '75 arrangement has one link on the battery feed/charge line. Usually located between the starter relay and the bulkhead connector.
upload_2021-5-1_19-46-39.png
 
Forgot to answer the other part. Usually it was 16 gage as most of the wires needing protection were 12 gage.
The ignition wire is mostly 16 gage but a) if it shorts to ground the engine ignition will have no power. b) turn the key to off and the electricity can't flow to the short.

If the R6 wire on your car is 10 ga, that's fine. Fuses and breakers are based on the weakest part of the circuit, not the strongest.
 
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