16.4 volts at the battery

[shadango]

Is the dash harness/bulkhead connector the original?

As far as I can tell yes....doesnt seem to be in bad shape, but with anything that old, trying to not "fix what aint broke" because I may break something...LOL

[734406pk]

Got yah! I would rather test the harness first before disturbing it. This way we can be 100% sure where the problem is.

[xtopfuel]

engine bay side only

[734406pk]

engine bay side only

Thanks! I remember reading in i prior post that the engine harness was replaced a some point. With electrical issues like this, I have found it is best to find the problem first, then do the repair. After that you can re-measure voltage drops to verify that you have corrected the issue.  Electrical issues are tough since you can't "see"  what's going on only measure it.

[shadango]

Just to stay current, I havent forgotten this thread.....just havent had the time to do the second stage of testing.  Was out of town last week at a big show. Then the kiddos were involved in stuff etc.......life. LOL

Gonna jump back on it as soon as I can find the time, hopefully this evening or tomorrow. i really do appreciate the ongoing help!

[shadango]

Ok so far:

A- 15.8 volts= You are over charging.
B- 0.018-0.026 ground side voltage drop= excellent! You have a clean ground path from the alternator to the battery.
C- .42-.50 Output side voltage drop= On the high side! Do you have an ammeter bypass installed btw? It's not causing your overcharging issue, but we should clean that up after the overcharge.

To continue:
Start the engine and turn on all accessories as before and set idle speed to 1200-1500 rpm

D- VR case voltage drop. Negative test lead to battery negative post. Positive test lead to the metal CASE (not an attaching bolt) of the VR. You may need to scratch a tiny bit of paint off the case to get a reading. Write down this reading as D.

E- Alternator F+ voltage drop. Positive test lead to the positive battery post, negative test lead to the BLUE alternator field wire terminal. Try to slip the test lead probe inside of the slip on connector for a good reading. Write down the reading as E.

F- VR sensing lead voltage drop. Now use your pin through the blue wire at the VR. Connect the negative test lead to the pin. Connect the positive test lead to the battery positive post. Write down this reading as F.

You can shut down the car now.

I suspect that the cause of the overcharging will be within these three test points. Post your readings or any questions when you can. Good luck and work safe!

Ok, just did this section

D - VR case voltage drop....I had to set the scale low to get anything.....got .000 to .001

E - Alternator F+ voltage drop .... had to swap my blue and green field wires to do this......got 1.2 to 1.4

F - couldnt get pin thru the actual wire...so I back probed the blue wire at the connecter with a safety pin.......got 1.4

[734406pk]

Quote:
Ok, just did this section

D - VR case voltage drop....I had to set the scale low to get anything.....got .000 to .001

E - Alternator F+ voltage drop .... had to swap my blue and green field wires to do this......got 1.2 to 1.4

F - couldnt get pin thru the actual wire...so I back probed the blue wire at the connecter with a safety pin.......got 1.4

Ok, nice job!

D= Very good! You have an excellent ground to the VR case.
E & F= The voltage drop here is very high. This is why the alternator is over charging.

Now on to find the resistance...
Looking at the new engine harness at the bulkhead connector,engine side,  you will see a blue wire on pin 23.
We need to connect the positive volt meter lead to the positive battery terminal and the negative lead back probe the blue wire connector at pin 23. Load the electrical system as before and write down this reading as G.
This test will check the integrity of the engine wire harness ignition power feed circuit. There's a substantial load on this blue wire.

[Bullitt-]

I'm diggin what your doing here Andy...
What I've read about as just not getting accurate signal to the VR in a outstanding step by step diagnosis. 

[734406pk]

Thank You Wade! Glad to help, Shadango needs a break with this overcharging issue! So far, low voltage to the blue "sense" wire is causing the VR to drive the alternator output voltage high out of range. The next step is to pinpoint where the resistance is. 

[xtopfuel]

  73440

[shadango]

Looking at the new engine harness at the bulkhead connector,engine side,  you will see a blue wire on pin 23.
We need to connect the positive volt meter lead to the positive battery terminal and the negative lead back probe the blue wire connector at pin 23. Load the electrical system as before and write down this reading as G.
This test will check the integrity of the engine wire harness ignition power feed circuit. There's a substantial load on this blue wire.

So it will be the same color blue (same wire) as at the VMR right?

[734406pk]

Quote:
So it will be the same color blue (same wire) as at the VMR right?

Yes it should be the same color Blue (same wire in the engine harness) on pin 23. This wire may have a stripe or tracer on it. It's energized with the key in the "run" position. Don't confuse with Pin 20, it could also be a blue (no stripe) wire but it powers the a/c compressor. Be sure to back probe the right one.

[shadango]

Quote:
So it will be the same color blue (same wire) as at the VMR right?

Yes it should be the same color Blue (same wire in the engine harness) on pin 23. This wire may have a stripe or tracer on it. It's energized with the key in the "run" position. Don't confuse with Pin 20, it could also be a blue (no stripe) wire but it powers the a/c compressor. Be sure to back probe the right one.

Thanks.  I dont have A/C.

Do you have a schematic handy as far Pin location numbers?  I am sure its in my manual somewhere if not....

[734406pk]

Here is a link to find and download your diagram, the .jpg was too large to post:
http://www.mymopar.com/72to76_wiring.htm

[shadango]

Here is a link to find and download your diagram, the .jpg was too large to post:
http://www.mymopar.com/72to76_wiring.htm

Yikes...looks like 'sghetti.  LOL

I was hoping more for a picture of the engine side of the bulkhead pointing out the numbering....but It wont be hard to figure it out....cant be more than one wire that color in that particular plug.....gonna check this reading hopefully tomorrow....if the weather holds out.

I suppose that this test will just confirm that the drop is somewhere between the connector at the bulkhead and the end of the VMR blue wire right? It will show a 1.4 or so voltage drop....And if it DOESNT , then the next step is to measure between the bulkhead connector and something inside the car?