Alternator wiring

[Mark1972]

This is likely the first of a few questions regarding wiring up my 1970 Satellite now that the 440 is in. I ordered a new engine wiring harness from Classic Industries. I also have a wiring diagram for my car. The wiring diagram shows a dark green wire going to field, and a dark blue wire goes to field, and then the battery wire(black)gets pinched between the two nuts. That's what my old harness was like, except when I hooked up the alternator wires with the old motor, I must have had the blue and green wires backwards, because it melted the wire. I replaced it, switched the wires, and no more problems. Now I've got the new wiring harness, and there are two blue wires going together into one connector, the lone green, and of course the battery wire. The diagram says both go to field, but doesn't specify which. Having melted the wires before, I don't want to make the same mistake again. So my questions are:
Why two blue wires instead of one on the old harness?
Why are the two field poles not marked specifically when they are obviously not the same?

Automotive electrical is a huge weak spot for me. I'm sure there is a simple answer. Thanks for the help.

 

[R413]

It is so simple! The field wires can go on either terminal. That’s not why your wire melted last time.

 

[Mark1972]

It is so simple! The field wires can go on either terminal. That’s not why your wire melted last time.

That's what worries me. I'd rather have made a mistake and then figured it out than not know why it happened. All I did was change the wires around and the problem was solved. Must have been something else I did. Anyway, appreciate the answer.

 

[RJRENTON]

R413 is correct....it does not matter which wire gets connected to the alternators field connections. The double blue wire brings 12 volts to the field; the green wire goes back to the voltage regulator. The voltage regulator completes the circuit thru an internal transistor to ground, via the green wire. This is why it is so important that the case of the voltage regulator is securely grounded. The regulator turns the alternator field current on/off to keep the alternator output voltage at 14.5 volts (+/-) depending on the battery's state of charge. To insure the regulator's case is grounded, I put the engine's ground wire under one of the regulator mounting bolts. Just my opinion of course.
BOB RENTON

 

[66Satellite47]

Bob is SO CORRECT, the voltage regulator grounding, really good is critical. Chased that for a long time on my '70 Barracuda (electronic regulator). Couple trips to the dealer that didn't figure it out. Eventually sanded the voltage regulator case & firewall at the mount bolt & added a second ground wire to the firewall. This also applies to the electronic ignition ECU.

 

[R413]

I cringe when I read that you sanded the firewall, that’s not where they ground. They ground at the bolt threads and under the bolt head. Have you EVER seen a factory installation have the paint sanded off of anything? NO and you will not, because it will rust and you will not have any grounding there anyway. And pissed off customers that their new car has rust trails coming out out from under all the electrical boxes.

Look at taillight attaching nuts, they have small barbs on the washer to aid grounding. So add star washers under the bolt heads if you want to help.

 

[493 Mike]

It is so simple! The field wires can go on either terminal. That’s not why your wire melted last time.

Yes they can but, the top spade terminal in the photo got the blue at the factory.
Mike

 

[Mark1972]

I'll make sure the voltage regulator is well grounded by making sure the screw holes and screws are clean and bare metal. It's coming along slowly.

 

[66Satellite47]

I cringe when I read that you sanded the firewall, that’s not where they ground. They ground at the bolt threads and under the bolt head. Have you EVER seen a factory installation have the paint sanded off of anything? NO and you will not, because it will rust and you will not have any grounding there anyway. And pissed off customers that their new car has rust trails coming out out from under all the electrical boxes.

Look at taillight attaching nuts, they have small barbs on the washer to aid grounding. So add star washers under the bolt heads if you want to help.

Yes, factory grounding is through the mounting screw threads. That assumes it creates a good ground. In my case that didn't work. My solution was not OEM or show quality, but it worked.

edit: My factory regulator grounding problem was intermittent, very frustrating to need to watch the ammeter to see if the alt was working. The fix was a stable ground.

 

[Cartel]

just passing by but 1 spade terminal is bigger than the other. Like F1 F2
If I were to guess, the green goes on the bigger brass connector

 

[70ChargerRT]

I cringe when I read that you sanded the firewall, that’s not where they ground. They ground at the bolt threads and under the bolt head. Have you EVER seen a factory installation have the paint sanded off of anything? NO and you will not, because it will rust and you will not have any grounding there anyway. And pissed off customers that their new car has rust trails coming out out from under all the electrical boxes.

Look at taillight attaching nuts, they have small barbs on the washer to aid grounding. So add star washers under the bolt heads if you want to help.

Yeah let’s use rusty bolt holes for a ground. Ill grind the F out my car if I want lol those barbed washers aint worth a **** especially with several layers of primer, base and clear coat and why would anybody have rusty trails coming out of from under the hood anyways? You spray your engine bay out at the car wash??? I’ll grind it, clean the bolt holes out the best I can and add dielectric grease and guess what no rusty trails and a good ground lol

 

[R413]

Well the barbed washers will touch on the voltage regulator not the firewall with all the bodywork and paint.

Like I said the bolt holes grounded for decades amd still function. No factory ever sanded the paint on the flat surfaces to lake a ground, and they made millions of cars, many that run as daily drivers parked outside for 10-15-20 years And hundreds of thousands of miles.

How many folks you know of with 300k mile daily’s and Cummins trucks. Have they all removed the grounded electricals and sanded all the paint off?

 

[Denham]

Yeah let’s use rusty bolt holes for a ground. Ill grind the F out my car if I want lol those barbed washers aint worth a **** especially with several layers of primer, base and clear coat and why would anybody have rusty trails coming out of from under the hood anyways? You spray your engine bay out at the car wash??? I’ll grind it, clean the bolt holes out the best I can and add dielectric grease and guess what no rusty trails and a good ground lol

Well the barbed washers will touch on the voltage regulator not the firewall with all the bodywork and paint.

Like I said the bolt holes grounded for decades amd still function. No factory ever sanded the paint on the flat surfaces to lake a ground, and they made millions of cars, many that run as daily drivers parked outside for 10-15-20 years And hundreds of thousands of miles.

How many folks you know of with 300k mile daily’s and Cummins trucks. Have they all removed the grounded electricals and sanded all the paint off?

 

[RJRENTON]

R413 is correct....it does not matter which wire gets connected to the alternators field connections. The double blue wire brings 12 volts to the field; the green wire goes back to the voltage regulator. The voltage regulator completes the circuit thru an internal transistor to ground, via the green wire. This is why it is so important that the case of the voltage regulator is securely grounded. The regulator turns the alternator field current on/off to keep the alternator output voltage at 14.5 volts (+/-) depending on the battery's state of charge. To insure the regulator's case is grounded, I put the engine's ground wire under one of the regulator mounting bolts. Just my opinion of course.
BOB RENTON

To those who DISAGREE with my comments, please state WHY you disagree. Perhaps those that disagree do not know how the Mopar charging systen operates. Inquiring minds want to know.....
BOB RENTON