help- blue field wire grounded?

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DJC

DJC

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Hello, hoping you can help.

Fresh /6 to 360 swap. Engine starts and runs, was running well. Then it started missing/hesitating and noticed the add-on voltmeter showing excessive charging ( around 16 volts ). Checked grounds, they were at zero. Was the original voltage regulator, so I replaced it as well as the ecu (also an older unit). Added ground wires from ecu and vr housings to battery ground just to make sure. Started car, fired right up. Voltmeter shows high charge (16v), factory battery gage is normal/centered (not bypassed, still original wiring setup). Shut it down, searched threads for diagnosis help. Battery voltage is 12.43 volts (new battery). I've closed the window that had 67Dart273's voltage check info, so I can't recall what led me to this finding, but with the blue field wire disconnected at alternator and at VR, multimeter connected to blue field at alternator end I'm showing continuity if I ground the other probe for the meter. I'm assuming that should not be. It's a new M&H engine side harness, I've visually inspected and can see no damage indicating a short. Haven't run it much for fear of damaging new vr or ecu. Original alternator with 360.

I'm going to keep searching but any help would be appreciated regarding that field wire.
 
Update, charging seems to have settled down to around 15 volts (add-on gage) or just right of center (factory instrument gage).

Still curious about that ground, though.
 
DJC said:
Update, charging seems to have settled down to around 15 volts (add-on gage) or just right of center (factory instrument gage).

Still curious about that ground, though.
Click to expand...
What it is reading at the battery?

Jake
 
I don't think your testing is valid. Ohmeter readings will "read' through the loads paralleled with the blue wire for example.

Your charge voltage is still "a bit" high and that is likely due to a bit of drop in the ignition harness.

Best way to check the blue is with everything hooked up "normal" and key in "run." This applies power to the blue, and the green regulator wire (field) will cause the field to draw current, which puts some load on the circuit. This is "good" as the loading helps show up voltage drop

Now withOUT disconnecting the blue, "back probe" that connector and see if it reads "same as battery."
 
67Dart273 said:
I don't think your testing is valid. Ohmeter readings will "read' through the loads paralleled with the blue wire for example.

Your charge voltage is still "a bit" high and that is likely due to a bit of drop in the ignition harness.

Best way to check the blue is with everything hooked up "normal" and key in "run." This applies power to the blue, and the green regulator wire (field) will cause the field to draw current, which puts some load on the circuit. This is "good" as the loading helps show up voltage drop

Now withOUT disconnecting the blue, "back probe" that connector and see if it reads "same as battery."
Click to expand...
Ignition in "run", everything plugged in, positive probe in blue connector and negative probe to negative battery shows minor fluctuating 8.2v.
 
That is LOW. "Here is why" low voltage to the ignition / regulator circuit causes OVER charging

In the girls we talk about on here, there is only ONE ignition switched power supply under the hood in "run" that is the (normally dark blue) "IGN1" wire coming out of the bulkhead connector

This feeds several things over the years depending on smog devices, etc, but generally, the ignition system, the VR "IGN" terminal, the alternator "light blue" field.

If that voltage is LOW this is ALSO the VR "voltage sense" and the VR tries to charge so that it rises to the setpoint, IE nominal 14V. So with the VR IGN terminal "happy" at 14V, the voltage drop backwards around to the harness to the battery results in HIGHER voltage to the battery.........by the amount of the measured drop.

Your 8V sounds like "it may change" that is, I bet if you start wiggling the bulkhead connector, the key, or the ignition switch connector, you will find that it goes higher/ lower

To put this another way, the normal way that I measure this drop is to probe the IGN feed as close to the VR as possible......and the blue field would do that, then put your other probe on battery PLUS. This is with the key in "run" and engine stopped. This gives you the amount of the drop directly. Again if you "wiggle test" you are likely to find out "just where" this might be
 
67Dart273 said:
That is LOW. "Here is why" low voltage to the ignition / regulator circuit causes OVER charging

In the girls we talk about on here, there is only ONE ignition switched power supply under the hood in "run" that is the (normally dark blue) "IGN1" wire coming out of the bulkhead connector

This feeds several things over the years depending on smog devices, etc, but generally, the ignition system, the VR "IGN" terminal, the alternator "light blue" field.

If that voltage is LOW this is ALSO the VR "voltage sense" and the VR tries to charge so that it rises to the setpoint, IE nominal 14V. So with the VR IGN terminal "happy" at 14V, the voltage drop backwards around to the harness to the battery results in HIGHER voltage to the battery.........by the amount of the measured drop.

Your 8V sounds like "it may change" that is, I bet if you start wiggling the bulkhead connector, the key, or the ignition switch connector, you will find that it goes higher/ lower

To put this another way, the normal way that I measure this drop is to probe the IGN feed as close to the VR as possible......and the blue field would do that, then put your other probe on battery PLUS. This is with the key in "run" and engine stopped. This gives you the amount of the drop directly. Again if you "wiggle test" you are likely to find out "just where" this might be
Click to expand...

OK, wiggle tested ignition key, wiring up column, connectors at column and both sides of bulkhead connector - no battery voltage showed. If I do nothing but turn on key and watch, it will slowly rise - it reaches a voltage (ie 8.23) then drops .2 or so volts, the rise to slightly higher (ie 8.28), then repeats this cycle up to about 9.21 (got tired of watching at that point but it was over a minute or so.
 
WOW. Where have you probed? The functional path is ----------from the ammeter..........to the welded splice in the black ammeter wire..........to the ignition switch connector...........through the switch.........out the switch connector on "IGN1"..........to the bulkhead connector...........through it.......and under the hood. At some point under the hood, near the ballast, it splits off to the various under-hood loads.

Time for a shop manual/ wiring diagram if you do not have one you can download several years, for free, at MyMopar

What year / model is the car?
 
67Dart273 said:
WOW. Where have you probed? The functional path is ----------from the ammeter..........to the welded splice in the black ammeter wire..........to the ignition switch connector...........through the switch.........out the switch connector on "IGN1"..........to the bulkhead connector...........through it.......and under the hood. At some point under the hood, near the ballast, it splits off to the various under-hood loads.

Time for a shop manual/ wiring diagram if you do not have one you can download several years, for free, at MyMopar

What year / model is the car?
Click to expand...

72 Valiant Scamp. Originally /6 now 360.

I do have a 1972 Chassis manual. So are you saying I should have battery voltage all along the path you mentioned above? With key in run position?

And thanks very much for your time, btw.

Dave
 
You bet. Ignition switch connector is easy to access I would start there. If the headlights are nice and bright, that shows that the RED ammeter feed through the bulkhead is likely OK, and that the "welded splice" is also likely OK

Here's the "MAD" article. This thing gives a good overview, regardless of what Slant Six dan thinks, and the diagram is an "easy" way to see basic power distro:

Catalog

amp-ga18.jpg


With the headlights on, you can also wiggle the bulkhead connector and see if they dim/ blink. Also reach up and feel the ammeter terminals if you can get your hand in there. See if they are warm or loose
 
67Dart273 said:
You bet. Ignition switch connector is easy to access I would start there. If the headlights are nice and bright, that shows that the RED ammeter feed through the bulkhead is likely OK, and that the "welded splice" is also likely OK

Here's the "MAD" article. This thing gives a good overview, regardless of what Slant Six dan thinks, and the diagram is an "easy" way to see basic power distro:

Catalog

View attachment 1715193942

With the headlights on, you can also wiggle the bulkhead connector and see if they dim/ blink. Also reach up and feel the ammeter terminals if you can get your hand in there. See if they are warm or loose
Click to expand...

Thanks for the help. I'll have to stop for the night soon, but I'll let you know what happens.:thankyou::thumbsup:
 
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