Looking for help with wiring a 1 field regulator to a 2 field alternator

[treebark]

I've seen a few posts around this topic, but none that have completely helped me understand what to do. I'm relatively new to working on cars - especially wiring - so answers that are "for dummies" would be appreciated.

I recently took over a 1968 Dodge A-100 pickup that my dad restored about 13 years ago. I put on a starter and a new battery and drove it three hours home, but now find that it's not charging. I took the alternator in to have it tested and it failed, so I bought a new one but now am unsure how to properly connect the wiring. The engine has been swapped from the original 6 cyl to a 360 LA.

The alternator that was on the truck had 2 field terminals and a BAT post.

The new/reman alt has the same connections, but also a dedicated GRD post.

The regulator mounted above the gas pedal is the original mechanical style. It has a dark blue wire to the top terminal from the fuse block, a brown ground wire and a light green field wire that both run to the alt.

Other threads have indicated that the second field terminal on the alt can be connected to the alt body/GRD post to get volts to the battery, but I'm not sure if I should also connect the ground wire from the regulator to that terminal or not? In other words, if I put a jumper wire from where I currently have the ground wire on the alt FLD terminal over to the GRD post will that get things working without causing damage to the system?

 

[Darter6]

Yes either field terminal can be connected to the ground post.
So as you stated the green field wire to one terminal and the other, wire a jumper to ground.

 

[treebark]

Yes either field terminal can be connected to the ground post.
So as you stated the green field wire to one terminal and the other, wire a jumper to ground.

Thanks! And just to confirm: keep the ground from the regulator attached along with the jumper wire, correct? Any concerns with this hook up causing any damage to any of the components (reg., alt., bat.) or can this be a permanent fix?

 

[4mulas]

You can shunt one field to ground by taking the insulator off the terminal and reinstalling the screw.

 

[treebark]

You can shunt one field to ground by taking the insulator off the terminal and reinstalling the screw.

This falls under my comment that answers "for dummies" are best for me... I don't know what you mean by "taking the insulator off the terminal and reinstalling the screw." I'm guessing you mean on the alternator, but do you mean the screw that is holding the second field terminal to the alternator housing? And is the insulator the small washer that is between the screw head and the terminal? Also, would that eliminate the need to have a jumper wire from that terminal to the ground post, or would that be in addition to that set-up?

 

[67Dart273]

I would not take the brushes apart to ground one. I would make CERTAIN (with a meter) the following:

With both field wires unhooked, take a meter and look for continuity between either of the field terminals and ground. It should be open/ infinity.

Next I would make up a short jumper from either field terminal and connect the other end to ground, leaving both field terminals "as they were."

WHY? Because this is what can confuse people and leads to burned wires. If at some point you forget, and thing maybe that is an isolated field (it is not "two field) you may connect a live wire to the grounded terminal by mistake

Second, if that old regulator fails, you can add one more wire and use a 70/ later regulator--which are better and which is what was used with the isolated field alternator.s

 

[treebark]

I would not take the brushes apart to ground one. I would make CERTAIN (with a meter) the following:

With both field wires unhooked, take a meter and look for continuity between either of the field terminals and ground. It should be open/ infinity.

Next I would make up a short jumper from either field terminal and connect the other end to ground, leaving both field terminals "as they were."

WHY? Because this is what can confuse people and leads to burned wires. If at some point you forget, and thing maybe that is an isolated field (it is not "two field) you may connect a live wire to the grounded terminal by mistake

Second, if that old regulator fails, you can add one more wire and use a 70/ later regulator--which are better and which is what was used with the isolated field alternator.s

I think I'm following this. When I touch the multimeter to the two field terminals there is continuity between them, but from either field to the ground post there is no continuity. I'll shorten the jumper wire and splice it to the existing ground with a new end once there's confirmation this looks correct.

 

[67Dart273]

The black from ground connects to the brush? That would be fine. What is the brown for?

 

[Dana67Dart]

What is the brown for?

That is a ground wire that runs back to the VR attaching bolt to the firewall

OPs dad was way ahead of all of us!

When you bought your new alternator what year did you specify?


Assuming the alternator was the only thing wrong with the charging system with the brown wire and the green wire attached to the ALT it should charge. Adding the dedicated ground on the ALT is not an issue.

if it is still not charging measure the voltage on the green wire to ground while the engine is running 6-8 V would be normal.

 

[treebark]

The black from ground connects to the brush? That would be fine. What is the brown for?

Sorry, if the picture is confusing. The black wire is not connected to anything yet, but my plan is/was to connect it to the brown wire so they're both connected to the FLD terminal and then to the GRD post.

That is a ground wire that runs back to the VR attaching bolt to the firewall

OPs dad was way ahead of all of us!
View attachment 1716411203


When you bought your new alternator what year did you specify?


Assuming the alternator was the only thing wrong with the charging system with the brown wire and the green wire attached to the ALT it should charge. Adding the dedicated ground on the ALT is not an issue.

if it is still not charging measure the voltage on the green wire to ground while the engine is running 6-8 V would be normal.

We used 1979 to try to get close. The engine stamp says its a 360 LA made between 1975 and 1993, but I can't find a specific date stamp. I have a new regulator available, but am trying to determine if it's needed or if the way the alternator is wired needs to be different than it was. Are you saying the brown wire attached to the second FLD terminal without being jumped to the GRD post should work? I wasn't seeing a voltage increase at the battery with things hooked up that way and thus started exploring...

"Adding the dedicated ground on the ALT is not an issue." Meaning it shouldn't be needed, or go ahead it won't hurt anything?

And now I'm questioning if the alternator I have is correct... the engine is newer, but the wiring is still 1968...

 

[67Dart273]

Well "correct" is a relative word. No reason you should not be able to us that one, and from your clarification, I'd say it is wired correctly. if it will not charge, disconnect the power (ign) wire and the green field wires at the VR and temporarily connect them together. It should charge full output if the wiring is continuous, and the alternator iis "good."

 

[Dana67Dart]

The reason I asked about the year the alt was for, is rebuilders take a square back isolated ground cores and convert them to work on a grounded field car, ( up to 1969? Ish)

Your car is setup to use an isolated field alt 70 something and newer (Brown ground wire) with a grounded field VR.

 

[Dana67Dart]

Adding the dedicated ground on the ALT is not an issue." Meaning it shouldn't be needed, or go ahead it won't hurt anything

Both!

The brown wire provides the ground, adding the black wire just doubles up the ground connection

 

[Dana67Dart]

BTW... the grounded field voltage regulators are susceptible to damage if the green wire gets grounded

You wanted alternators for "dummies"

(they are on MYMOPAR.com but easier to find this way)

Google "Chrysler master tech video" & a key word like "alternator"

"Chrysler master tech video alternator"


results...

These videos are corny but do a GREAT job explaining the systems of our cars (and Vans)


up through 1969



1970 and newer

 

[treebark]

Life took me away from things for a bit...

With both field wires unhooked, take a meter and look for continuity between either of the field terminals and ground. It should be open/ infinity.

I've spliced the black jumper wire in to the brown ground wire that is currently connected to the second FLD terminal. I still have continuity between the two FLD terminals, but also between either FLD terminal and the GRD post now. Is that what's expected?

BTW... the grounded field voltage regulators are susceptible to damage if the green wire gets grounded

Again, electrical "dummy" here that doesn't want to cause more harm than good. If the GRD now has continuity to the post the green wire is on is that bad?

If this looks correct to all of you I'll give it a try even though I don't understand why the GRD and FLD being connected and having continuity between each other is what is wanted...

 

[treebark]

I decided to pull the cover off the old regulator and found the wire for the upper contact is melted.

Remember, this is how my Dad had it wired: green wire to one FLD, brown ground wire to the other FLD. No jumper wire to the case. I don't have the old alt any more (turned in for core) so I don't know if it had been modified in some way.

What it makes me wonder though is if there's continuity between the field and ground wires would that possibly burn out the regulator?

 

[abodyjoe]

..........................

 

[RustyRatRod]

You can shunt one field to ground by taking the insulator off the terminal and reinstalling the screw.

That's how I do it. Works good.

 

[Dana67Dart]

The burned wire in the VR is the reason you don't have charging.


It's a fusable link to blow before wires melt.

Replace the VR.

You need a grounded field vr. Get one for your vehicle year, NOT the engine or alternator.

The photo in post 17 is for an isolated ground VR

You currently have and are wired for a grounded field VR.

 

[4mulas]

This falls under my comment that answers "for dummies" are best for me... I don't know what you mean by "taking the insulator off the terminal and reinstalling the screw." I'm guessing you mean on the alternator, but do you mean the screw that is holding the second field terminal to the alternator housing? And is the insulator the small washer that is between the screw head and the terminal? Also, would that eliminate the need to have a jumper wire from that terminal to the ground post, or would that be in addition to that set-up?

Yes is the answer to all those questions. No jumper wired required afterwards

 

[treebark]

The burned wire in the VR is the reason you don't have charging.


It's a fusable link to blow before wires melt.

Replace the VR.

You need a grounded field vr. Get one for your vehicle year, NOT the engine or alternator.

The photo in post 17 is for an isolated ground VR

You currently have and are wired for a grounded field VR.

Yes, I've seen that what is posted in #17 is an updated 1970 and newer wiring that many people do with an electronic regulator replacing the mechanical one I have now.

I have a new mechanical/grounded field VR that exactly matches the one the wire melted in. The thing I don't understand at the moment is why that wire melted? If the fuse box has the wrong amp fuse in the alt/reg slot could that be the problem? The diagram I found shows it should be a 6A fuse, but I think when I checked to see if anything there was blown it was a 30A fuse, and I don't know why Dad would have done that. The specs on the new VR say it is a 15 amp unit. Would that mean 15 amp is the limit it can handle before blowing like the old one did? I'd like to not have the VR fail again, but don't know what else to check to determine if something else might be wrong.

The new VR and new Alt are wired up as shown in the pictures I've already shared - essentially the same way as my Dad had them just with the additional jumper wire between the brown ground wire and the GRD post on the new alt. Anything else I should be checking before reconnecting the battery and starting the truck?

 

[Dana67Dart]

. The thing I don't understand at the moment is why that wire melted?

If the output (Green wire) got grounded that could have done it

 

[treebark]

If the output (Green wire) got grounded that could have done it

You mentioned that earlier... this electrical dummy doesn't really understand what that means. Can you give me an example of how that green field wire might become grounded? And what's the difference between that and what I'm doing by connecting the second field terminal to the ground thus creating continuity between the ground and the field wire/terminals? I'm also still curious if the 30 amp fuse allowing too much flow to the ignition side of the VR rated for 15 amps could fry it?

 

[Dana67Dart]

You mentioned that earlier... this electrical dummy doesn't really understand what that means. Can you give me an example of how that green field wire might become grounded

Ignition key is on, the green field wire has been disconnected from the alternator, it inadvertantly touches the metal housing of the alternator.

 

[Dana67Dart]

I'm also still curious if the 30 amp fuse allowing too much flow to the ignition side of the VR rated for 15 amps could fry it

All a fuse does is protect the wires it does not limit the amount of current

Your house wiring has 120V to each outlet, each outlet is CAPABLE of providing up to 15 amps of current. If you plug in an LED table lamp it only requires 1 amp, if you plug in a hairdryer it requires 10 amps both work fine. Plug in 2 hairdryer and circuit breaker (think fuse) trips. if it did not the wires which are only capable of caring 15 amps would heat up and start to melt the insulation, create a short that could burn your house down.