Stop in for a cup of coffee
Fix your under hood alternator wiring first... Not that hard, I'll walk you through it...
I like to go one gauge/step above the factory wiring just for safety....
First get some 16 gauge dark blue wire... Put a flat blade female terminal on it... You can crimp it on, or I like to solder them for better durability.... But for now, crimp the flat blade female terminal on one end of the wire and attach it where the blue field wire comes off the alternator... Just run this wire separate for now, you can tuck it in the wiring harness and tape it later if you wish, but this will get you running...
Here is the female flat blade connector that you will need for this end that goes to the alternator:
Now run that wire down the passenger side valve cover to the firewall and you can use a small piece of tape to help run it along the existing wiring harness... Run it down the pass valve cover to the firewall and along the harness on the firewall across the engine compartment to the ballast resistor Taping it every 10" or so along the way to keep it following the wiring harness... Then when you know how long of wire you will need, cut it off and then put a piggyback terminal on the end that attaches to the ballast resistor.... a piggyback terminal looks like this:
* Make sure to put the shrink wrap on the wires before you connect the two ends together because you can't put it on after the wires are done....
You can get piggyback terminals from your local NAPA store:
https://www.napaonline.com/en/p/GRO...jpG0Dl2ea4hGekdeXeuk-1637368319-0-gaNycGzNB1E
After attaching the piggyback terminal on the wire, pull the existing blue wire off the ballast resistor and attach the piggyback terminal to that side of the ballast resistor, then attach the factory wiring to the top spade of the piggyback terminal...
Now you have a good wire and connection to one of the field wires for the alternator...
Next, get some dark green 16 gauge wire and another regular female flat blade and make an end to go on the other field wire of the alternator...
Run this green wire along with the blue one that you just ran, down the passenger side valve cover to the firewall and across the firewall to the voltage regulator... Take the connector for the voltage regulator and clip the green wire, leaving enough wire length on the end of the connector side that plugs into the voltage regulator... Solder the green wire that you just ran to the green wire that you left on the voltage regulator connector and then shrink wrap and tape over the splice to insulate it... Then connect the connector to the voltage regulator...
Here's a thread that will show you how to do a basic wire splice with solder:
How to do a Basic Wire Splice
Now get some 10 gauge black wire for the wire that goes to the stud and nut on the back of the alternator... Get a 10 awg 5/16 ring terminal to crimp on the end of the black wire that goes to the stud on the alternator... It looks like this:
NAPA carries these also...
https://www.napaonline.com/en/p/NW_721323?impressionRank=6
Connect the end to the alternator and run the wire down the passenger side valve cover and along the firewall as you did with the other two... Run this wire down to the bulkhead connector... Find the "P" terminal on the bulkhead connector and cut the wire coming out of it leaving about 2" - 3" for you to connect to... Strip 1" - 1 1/2" of wire off the end that goes to the bulkhead connector and the new wire that you just ran, and solder them together... Then shrink wrap and tape to insulate it from shorting...
Here is the bulkhead connector "P" wire that you are looking for:
Here are the 72 Plymouth wiring diagrams to follow... If I remember correctly, you have a 72...
No highlights:
With highlights:
If you need larger size pics for the wiring diagrams above, PM me your email and I can email them to you...
Now your under hood charging system wiring is all brand new and won't be a problem any more... The original wires are too old and stiff and can break too easily that could be causing some of your problem... Now you have eliminated the old wiring as your problem and can focus on the alternator and regulator....
Good luck, we're all counting on you...
Fix your under hood alternator wiring first... Not that hard, I'll walk you through it...
I like to go one gauge/step above the factory wiring just for safety....
First get some 16 gauge dark blue wire... Put a flat blade female terminal on it... You can crimp it on, or I like to solder them for better durability.... But for now, crimp the flat blade female terminal on one end of the wire and attach it where the blue field wire comes off the alternator... Just run this wire separate for now, you can tuck it in the wiring harness and tape it later if you wish, but this will get you running...
Here is the female flat blade connector that you will need for this end that goes to the alternator:
Now run that wire down the passenger side valve cover to the firewall and you can use a small piece of tape to help run it along the existing wiring harness... Run it down the pass valve cover to the firewall and along the harness on the firewall across the engine compartment to the ballast resistor Taping it every 10" or so along the way to keep it following the wiring harness... Then when you know how long of wire you will need, cut it off and then put a piggyback terminal on the end that attaches to the ballast resistor.... a piggyback terminal looks like this:
* Make sure to put the shrink wrap on the wires before you connect the two ends together because you can't put it on after the wires are done....
You can get piggyback terminals from your local NAPA store:
https://www.napaonline.com/en/p/GRO...jpG0Dl2ea4hGekdeXeuk-1637368319-0-gaNycGzNB1E
After attaching the piggyback terminal on the wire, pull the existing blue wire off the ballast resistor and attach the piggyback terminal to that side of the ballast resistor, then attach the factory wiring to the top spade of the piggyback terminal...
Now you have a good wire and connection to one of the field wires for the alternator...
Next, get some dark green 16 gauge wire and another regular female flat blade and make an end to go on the other field wire of the alternator...
Run this green wire along with the blue one that you just ran, down the passenger side valve cover to the firewall and across the firewall to the voltage regulator... Take the connector for the voltage regulator and clip the green wire, leaving enough wire length on the end of the connector side that plugs into the voltage regulator... Solder the green wire that you just ran to the green wire that you left on the voltage regulator connector and then shrink wrap and tape over the splice to insulate it... Then connect the connector to the voltage regulator...
Here's a thread that will show you how to do a basic wire splice with solder:
How to do a Basic Wire Splice
Now get some 10 gauge black wire for the wire that goes to the stud and nut on the back of the alternator... Get a 10 awg 5/16 ring terminal to crimp on the end of the black wire that goes to the stud on the alternator... It looks like this:
NAPA carries these also...
https://www.napaonline.com/en/p/NW_721323?impressionRank=6
Connect the end to the alternator and run the wire down the passenger side valve cover and along the firewall as you did with the other two... Run this wire down to the bulkhead connector... Find the "P" terminal on the bulkhead connector and cut the wire coming out of it leaving about 2" - 3" for you to connect to... Strip 1" - 1 1/2" of wire off the end that goes to the bulkhead connector and the new wire that you just ran, and solder them together... Then shrink wrap and tape to insulate it from shorting...
Here is the bulkhead connector "P" wire that you are looking for:
Here are the 72 Plymouth wiring diagrams to follow... If I remember correctly, you have a 72...
No highlights:
With highlights:
If you need larger size pics for the wiring diagrams above, PM me your email and I can email them to you...
Now your under hood charging system wiring is all brand new and won't be a problem any more... The original wires are too old and stiff and can break too easily that could be causing some of your problem... Now you have eliminated the old wiring as your problem and can focus on the alternator and regulator....
Good luck, we're all counting on you...