Low voltage at gauge, no charge?

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70SwingerGuy

70SwingerGuy

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Fired up the (until now running beautiful)70 swinger today, 340, MSD ignition, and right away noticed that my Autometer voltmeter wasnt showing around 14 anymore, but a hair over 12 without fluctuation. Took it for a quick drive around the block and no change, half a block away from home, I hear a slight FZZZZ behind my dash with what I think was a burning smell/possible slight smoke, got it into the garage and shut down with a slight knocking/detonation, which it never does. Subsequent run/stops have resulted in a slight ticking/knocking(about a dozen then stops) in the motor while being shut down, which again, it never has done. I havent pulled the dash bezel yet, but I was following the troubleshooting steps found in this post:
testing voltage regulator and this is what I found:
- unclipped the green field wire at the alt and grounded it, with the key in "run" without starting, voltage at the blue field wire was just 11.69v, battery was at 12.52 disconnecting/connecting the clip on the green terminal resulted in sparks as should be. Started the motor with my voltmeter on the battery and the voltage dropped to 12.4 and didnt increase.
- started the engine with the clip lead still installed, voltage at battery was 12.42, at the alternator bat post, it fluctuated between 27-28v
-disconnected the VR connector and the blue lead showed 11.69v and the battery was 12.59
-tested the green field wire for continuity with success.
- internal Autometer voltmeter stays a hair over 12v and doesnt move
The voltage regulator that I have looks to be the cheap silver one with made in China on the back; Ive watched a vid or two that say NOT to put these cheapos on, that they can be dangerous, and to only use the genuine Mopar regulators.
Im betting that the VR crapped out, dont know about behind the dash or the knocking yet
Any opinions/ideas/suggestions?
Edit: Its also highly recommended to ground the VR, is it ok just to run a ground wire from one of the mounting bolts on the VR to a ground source, rather than just rely on the mounting bolts for the ground?
 
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I would "guess" perhaps the low voltage due to the no charge condition might be making the ignition do some funky things causing the knock/detonation.
 
You mentioned 27-28V?? That will fry stuff for sure. I run a seperate ground from underhood voltage reg direct to batt -ve.
Dbl chk/clean connections at bulkhead connector. You should crawl under dash to inspect. Especially after noise/smell.
 
your best friend for grounds

grounding brush.jpg
 
4spdragtop said:
You mentioned 27-28V?? That will fry stuff for sure. I run a seperate ground from underhood voltage reg direct to batt -ve.
Dbl chk/clean connections at bulkhead connector. You should crawl under dash to inspect. Especially after noise/smell.
Click to expand...
Very good ideas, gonna do them all :)
 
70SwingerGuy said:
Fired up the (until now running beautiful)70 swinger today, 340, MSD ignition, and right away noticed that my Autometer voltmeter wasnt showing around 14 anymore, but a hair over 12 without fluctuation. Took it for a quick drive around the block and no change, half a block away from home, I hear a slight FZZZZ behind my dash with what I think was a burning smell/possible slight smoke, got it into the garage and shut down with a slight knocking/detonation, which it never does. Subsequent run/stops have resulted in a slight ticking/knocking(about a dozen then stops) in the motor while being shut down, which again, it never has done. I havent pulled the dash bezel yet, but I was following the troubleshooting steps found in this post:
testing voltage regulator and this is what I found:
- unclipped the green field wire at the alt and grounded it, with the key in "run" without starting, voltage at the blue field wire was just 11.69v, battery was at 12.52 disconnecting/connecting the clip on the green terminal resulted in sparks as should be. Started the motor with my voltmeter on the battery and the voltage dropped to 12.4 and didnt increase.
- started the engine with the clip lead still installed, voltage at battery was 12.42, at the alternator bat post, it fluctuated between 27-28v
-disconnected the VR connector and the blue lead showed 11.69v and the battery was 12.59
-tested the green field wire for continuity with success.
- internal Autometer voltmeter stays a hair over 12v and doesnt move
The voltage regulator that I have looks to be the cheap silver one with made in China on the back; Ive watched a vid or two that say NOT to put these cheapos on, that they can be dangerous, and to only use the genuine Mopar regulators.
Im betting that the VR crapped out, dont know about behind the dash or the knocking yet
Any opinions/ideas/suggestions?
Edit: Its also highly recommended to ground the VR, is it ok just to run a ground wire from one of the mounting bolts on the VR to a ground source, rather than just rely on the mounting bolts for the ground?
Click to expand...
OK let's start over. What this sounds like is that you HAVE A BREAK in the output or "charge" wire from the alternator to the battery


So the basics of what you want to do is this:

1...Determine if the output/ charge path from the alternator to the battery is OK

2...Determine if the VR is OK and wired and working OK

3...Determine if the alternator is working, wired OK, and operating OK

So to test the alternator, sounds like you successfully checked for power at the blue field (which is quite simply same as switched 12V or "ignition run"

Now what you want to do is take a jumper and remove the green field wire, and ground that alternator field terminal. With the key "in run" that will cause full field current and if the alternator is healty, will cause full charge output.

So double check---ground the field as I just mentioned, and re check battery voltage and re check the output post at the alternator. If the battery is still below 14V with the engine "fast idle," but if the alternator is still way high, you have a break in the charge wire circuit

Do you have stock wiring, do you still have the ammeter? If so that entire circuit is suspect. The bulkhead connector terminals for the black output wire and for the red ammeter wire, the ammeter itself, in rare cases, the welded splice in the ammeter circuit up near the cluster., and the eyelet connectors at the alternator and at the ammeter., and whatever wiring gets the fuse link to the battery.

IF THE accessories, lights, etc, still seem to work OK, then some of that is eliminated. This leaves only the welded splice and bulkhead connector terminals and the alternator black wire and end eyelet.

HAVE YOU smelled anything, smoke, heat, etc? That is a clue

Read this

and this diagram from the same page is the simplified ammeter path

amp-ga18.jpg

In the above diagram, note that as you follow the RED ammeter wire from the battery, fuse link, through the bulkhead connector, ammeter, out on the BLACK ammeter wire and to the WELDED SPLICE, that path must be good for stuff like the accessories and headlights, brake lights, etc to work. But AFTER that welded splice, the black continues on, on out through the bulkhead connector on BLACK, and to the alternator output. That last section is likely the problem.

If you do not have a factory service manual, run over to MyMopar.com and download the closest one you can find. You may have to settle for Plymouth vs Dodge, etc, and also while there, go to the wiring section, and download the aftermarket wiring diagrams. Those are not as detailed or complete, but often easier to follow
 
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67Dart273 said:
Do you have stock wiring, do you still have the ammeter? If so that entire circuit is suspect. The bulkhead connector terminals for the black output wire and for the red ammeter wire, the ammeter itself, in rare cases, the welded splice in the ammeter circuit up near the cluster., and the eyelet connectors at the alternator and at the ammeter., and whatever wiring gets the fuse link to the battery.
Click to expand...
Aside from the MSD electronic ignition, it appears to be relatively stock, with the addition of some aftermarket Autometer gauges.
The ammeter is still there and connected, I just put in a replacement fuel gauge with the IVR upgrade, and a new tach so I know this to be true.
67Dart273 said:
IF THE accessories, lights, etc, still seem to work OK, then some of that is eliminated. This leaves only the welded splice and bulkhead connector terminals and the alternator black wire and end eyelet.
Click to expand...
Preliminary check of the accessories show that everything(with the exception of the pass front signal light group, which wasnt working before) is working EXCEPT for the headlights, but the dash lights, aftermarket gauge lights, and taillights come on when the headlight switch is on, headlights were working fine before.
67Dart273 said:
HAVE YOU smelled anything, smoke, heat, etc? That is a clue
Click to expand...
I heard a slight "fzzzz" sound behind the dash cluster, and me and the wife both thought we smelled a bit of smoke, and I wasnt sure but I thought I may have seen some in the air.
I think it may be notable to mention that the voltage was low/not moving on my gauge as soon as I started the car, it wasnt until after running it for a few minutes that the sound/smell occurred.
That MAD link has a WEALTH of great information, thank you for this!
 
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Darn, man. If the headlights don't work this sounds like probably the welded splice has broken. You will have to pull the cluster to check. the welded splice is a few inches away from the ammeter black wire termination, wrapped up in the dash harness. Once you get the cluster out, you can unwrap the harness working back from the ammeter. Follow that big black back

First one of these I ever found was in the early 70's in a friend's 68 RR. We had the cluster and part of the wiring torn out of the dash in his apartment parking lot. He was beginning to think I was an idiot AND I WAS TOO!!!! LOL
 
67Dart273 said:
Darn, man. If the headlights don't work this sounds like probably the welded splice has broken. You will have to pull the cluster to check. the welded splice is a few inches away from the ammeter black wire termination, wrapped up in the dash harness. Once you get the cluster out, you can unwrap the harness working back from the ammeter. Follow that big black back
Click to expand...
So what could cause that splice to actually break and let go?? The night before I had to "dimple" one the pipes of my new headers, so possibly the shock/vibration of hitting it with the hammer may have caused it to break?
I've had the cluster out a few times recently, so Ive gotten pretty good at it at least :)
What would you recommend for a proper fix of that weld? Also, would bypassing the ammeter by joining the red and black wires be recommended at this stage? Im not sure I understand where the danger lies in the ammeter, I understand that the circuit is a long one from battery to gauge to alternator, but is it the gauge itself that may fail and start a fire, or somewhere else in the wiring along that path?
Thank you again for your help and information, its appreciated and Im learning alot :)

67Dart273 said:
First one of these I ever found was in the early 70's in a friend's 68 RR. We had the cluster and part of the wiring torn out of the dash in his apartment parking lot. He was beginning to think I was an idiot AND I WAS TOO!!!! LOL
Click to expand...
Luckily Im in my garage! I also had a 68 RR many a moon ago, my first mopar, I miss that car.
 
The danger of the ammeter circuit is that the entire end to end circuit/ harness/ connections AND THE meter is marginal. They mostly worked OK with smaller alternators for the expected life of these cars.

The wire size was marginal, the bulkhead connector terminals were never designed for that kind of amperage, and the ammeter itself can loosen up and cause problems.

But now that they are antiques, now that people install big alternators, big stereos, etc etc, and now that the connector terminals have had half a century to oxidize, things get worse.

You need to repair or bypass the bulkhead connector terminals, not just the ammeter terminals.
 
@67Dart273 Ive been reading the MAD links that you provided, and they are providing a lot of good information. I have a question about the splice of the two 10g(red/black) wires which join to the 16g fusible link, in the pic they provide, they dont show how they spliced and joined all three pieces securely, have you done this before, can you recommend a way to do this?
amp-ga36.jpg
 
Actually I should have qualified. Most of us here do not do that bypass as shown. Rather, I usually mention it is a good overview to the what happens and why

Simply, bypass the ammeter by fastening the ammeter wires together or fix it by soldering the studs to the shunt and make sure the ammeter wires are "good," and fix the bulkhead connector terminals, either by replacement, or by running wires straight through the connector body.

Then after doing the above, run a BIG fused or fuse link protected bypass wire direct from the alternator output to the battery
 
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