Bulkhead Disconnect #19 Engine Compartment

[Dale]

So, in understanding #19, I have a black wire labeled R6 18BK that routs to the Ignition terminal on the Voltage Regulator. I also have a red wire labeled J10 16RE routing to the single(2 terminal) Ballast Resistor, both routing from the engine compartment bulkhead disconnect #19. What is confusing to me is that, at the J10 16RE Resistor connection, my orange FLD wire from my Alternator is also joined to this connection location, which looks like a factory connector. In reviewing the Dodge Trucks SM for my 1971 W100, I don't see this orange FLD wire connection in the Specifications Diagram Chapter. I have the Output connection, FLD connection, and GND connection on my Alternator. The ALT GND wire is identified as A3 18LG and routs to the FLD on the Voltage Regulator terminal. This truck is converted to electronic ignition.

Any help about the orange FLD wire would be helpful!

[Dale]

Does anyone experienced know why I should not follow the Specifications Diagram for my W100 as outlined in the Dodge Trucks SM even though I'm converting to electronic ignition. The truck wire harness is factory, so most of the knowledge is universal to my service manual. Just need a vote of confidence and any experience here. Defeat is not an option!

Have a great day! Thanks!

[Dale]

So that don’t look like a factory connection at the orange ALT wire to the red wire at the Ballast Resistor terminal after all.

[Dale]

First, I believe I have a 3-wire alternator. Those wires are the BATT wire, FLD wire, GND wire. Its the exact alternator in the Dodge Trucks Service Manual.

[dodgeboykim]

First, I believe I have a 3-wire alternator. Those wires are the BATT wire, FLD wire, GND wire. Its the exact alternator in the Dodge Trucks Service Manual.

Incorrect. Link shows correct hookup for dual field connections. If you are using a dual field alternator on an older single field truck one terminal can be grounded to make it work work older regulator. Some alternators are dual field but have one terminal already grounded.

https://www.google.com/imgres?imgurl=ht ... mrc&uact=8

[Dale]

Appreciate that! I made sure I know I have a Single Field alternator, and not a dual field alternator. So, from the back of my alternator, I have a light green wire coming from the GND location to the electronic voltage regulator (assuming its a electronic VR). Next is a black wire from the VR leading into the #19 bulkhead disconnect, where the red wire also comes from routing to the positive on the ignition coil. My only guess as to where the orange field wire from the single field alternator hooks up/leads back to would be into Ignition 1 terminal of the ignition switch via J10 16RE from the ballast resistor terminal. This Dodge Trucks SM 1969-71 don't include anything on electronic ignitions.

[PwrWgnDrvr]

There is no such thing as a "dual field" alternator!
They are both exactly the same, both have 2 lugs, one of which is connected to each end of the single field winding. The difference is simply that one has the negative lug grounded to the case of the alternator and the other has the negative lug isolated from ground and connected to the VR. If you simply look in the FSM you will see the correct terminology, which is: "Isolated Field Alternator".

[Dale]

Thanks for the clarification! Isolated Field Alternator. I think I got it! Probably should hook up the battery and get the test light out.

www.mymopar.com/index.php?pid=79

[dodgeboykim]

There is no such thing as a "dual field" alternator!
They are both exactly the same, both have 2 lugs, one of which is connected to each end of the single field winding. The difference is simply that one has the negative lug grounded to the case of the alternator and the other has the negative lug isolated from ground and connected to the VR. If you simply look in the FSM you will see the correct terminology, which is: "Isolated Field Alternator".

So I screwed up on name. I've heard long time Chrysler mechanics use that term. Not gonna lose sleep over it. Dual output connections. How's that. d

[PwrWgnDrvr]

Don't lose sleep - at our age sleep is very important!
Dual output won't work either, cuz there is only 1 output. The other is an input.
Many mechanics are just that - mechanics. They don't always have a full understanding of how stuff works, only how to assemble or fix what's broke.
"wideblock" is another one of those incorrect terms....no such thing.
The reason for the confusion with the alternators is because the older style puts the regulator in series, between the battery + and the field coil positive lug....so to complete the circuit, the field coil neg lug is simply grounded to the case.
The newer style connects the positive lug directly to +12v from the battery and the regulator is placed in series between the negative lug and ground. Thus, the field coil is "isolated" (from ground) by the battery on one side and the regulator on the other. Simple, eh?

[Dale]

Thanks PwrWgnDrvr, I'm really doing my best to research and learn about my Dodge truck! I could have got a truck that didn't need anything, but fell in love with my W100 the first time I seen it. It is coming along pretty well, and I'm excited about fixing the wiring mess! I figured, from the battery and in the engine compartment would be the best place to begin with the wiring issues, into the bulkhead disconnect, and into the cab.

So now, I have the alternator figured out, and can move on to the headlamp switch. Isolated field alternator. The GND is grounded to the alternator case.

[PwrWgnDrvr]

.... Isolated field alternator. The GND is grounded to the alternator case.

I wasn't clear enough.
In the isolated field system, (newer style - 69-71), GND is NOT grounded to the case. That's why it has the green wire connected to the lug and going to the electronic regulator.