Funky alternator wiring- '73 Duster

[69bronzeT5]

The wiring in my Duster has been confusing the heck out of me, well the alternator wiring to be exact. All of the correct alternator wiring is there however there is one extra black wire. It's a thick one. I originally thought it was an extra wire that ran along the alternator harness but it's not, it comes out of the harness. It dosen't go anywhere towards the alternator either. It just comes out of the harness and then it's capped off. I've been looking at other cars at shows but I don't see the wire anywhere! Any idea what this wire could be?

 

[pettybludart]

Maybe for A/C?

 

[Rengo]

looks to be jerry rigged, you can always try to buy new wires for everything

 

[cudajim]

There's way too much tape on your wiring... but I would venture to say your extra wire may be for an old air conditioner system.

 

[340mopar]

Factory A/C systems use a seperate harness so I don't beleive it is that. Possibly an aftermarket A/C? Were does it it go at the other end? I wonder if it was a ground wire?


Chuck

 

[abodyjoe]

Factory A/C systems use a seperate harness so I don't beleive it is that. Possibly an aftermarket A/C? Were does it it go at the other end? I wonder if it was a ground wire?


Chuck

i agree. and smaller gauge. ya never know what someone could have done over the years. call year one and replace that garbage before you run into more problems..

 

[goldduster360]

You sure that is not the original alternator wire(batt)? The wire attached to your alternator now looks pretty hefty to me for an original.

 

[HemiPar]

I would have to agree with goldduster. Looks like the black wire to alt has been replaced at some point. Has your amp gauge been bypassed? if so that may be the extra wire there. just my .02

 

[69bronzeT5]

A new alternator wire could very well be it. It's never had A/C in it's life as far am I'm aware. No idea if the amp gauge is by passed....it seems to work though.



To replace that one harness.....what's the name of it?

 

[RPM]

Interesting that I just read this. I have on too on my '74 Duster. I am still using the slant 6 wiring on the v8. There is a black hot wire that is in about the same location as yours. I too thought it was to be for the alt, but its not. It has been capped off for a long time. My car was never a A/C car, and this is in the factory harness.. no one added it in. I havent found it on any of the old wiring diagrams either. I have no clue what else would need a constant hot lead.... so its tucked in the harness for now.

-RPM

 

[Dusterdude72]

Factory hot for the choke maybe?

 

[Paul Garcia]

I also have a 73 DusterAnd that black wire is confusing me as wellMy electrical system is working fine now that I put a voltage regulator so I'm going to leave it

 

[Mattax]

I also have a 73 DusterAnd that black wire is confusing me as wellMy electrical system is working fine now that I put a voltage regulator so I'm going to leave it

Paul,
The heavy gage black wire is alternator output.

Lets break this up by first covering what the black wire does. Then we'll cover what the other two alternator wires do.

Cars have two power sources: Battery & Alternator.
Power flows from whichever one can supply at the higher voltage.
> Battery can supply power at approximately 12.5 Volts.
> Alternator can supply power at approximately 14 Volts when its running.

The output wire from the battery and the one from the alternator are joined at the main splice. From that junction power is fed to the key switch, fuse box, headlight switch.
In the illustration below the main junction is represented by a solid black dot.

All of the wires joined at the main splice are connected to the battery positive. They are always hot!

How the alternator supplies and gets power:
When the engine is running the ignition needs power.
Current flows from the high voltage power supply, the alternator, through the key switch to the ignition.

The voltage regulator senses the voltage in the blue wire (labeled J2B).
Inside the regulator is basically a switch. Opening and closing the switch makes and breaks power to create the electromagnetic field inside the alternator.

More about the isolated-field alternator here: Identifying Chrysler Alternators (1960-1976)

 

[67Dart273]

You sure that is not the original alternator wire(batt)? The wire attached to your alternator now looks pretty hefty to me for an original.

^^I think this^^ It may have been damaged, or a "work around" for the popular bulkhead bypass. Frankly as chopped up as that all looks "it needs more work" Might be practically repairable and might not

If you don't have a factory service manual, go to MyMopar and download one.

 

[Paul Garcia]

Thanks man,ill definitely redo the wiring on my Duster,appreciate the knowledge.

 

[Mattax]

Thanks man,ill definitely redo the wiring on my Duster,appreciate the knowledge.

He's looking at the first poster's photos.
You would need to post your car's photos.
Also beware that 1973 had some options where the altnator output wire was run a little differently.
One version that has shown up here on FABO several times came with cars equiped with a rear window electric defrost grid.

 

[6pak]

I don’t know why you just cut the taped harness back and chase the wire to where it goes.
Or put a meter on it and ohm out where it goes.
Charge would go back to battry.
Somone may have found it necessary to ground the alternator.

These cars are old, each owner over the years had their opportunity to dick it up.

If charging system works, cut the harness tape back and rip it out.
and tape it back up.

 

[BillGrissom]

You would probably do better to make your own custom charging harness. One reason is that the factory design running the large ALT current thru the bulkhead terminals to the dash ammeter causes big problems (melted plastic). They had the bulkhead right in 1963 and 1965. Search "MAD Bypass". In my 1965 Dart (avatar), I used the charging harness from a Magnum V-8, but route the ALT wire thru an underhood fuse/relay box (from 1990's Jeep). Consider the "big picture" before jumping in.