Ammeter waving when ignition is on.

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Traxfish

Traxfish

Convertible Cruiser
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St. Louis, Missouri
I've got an electrical issue with my 1968 Barracuda. The Ammeter will drop, wave for a second, then return to normal and it does this cyclically. There is an audible click every time it drops and every time it resets. Headlights dim with the waving. It does this whenever the ignition is on or on accessories.
The gauges at the time were overreporting, going strait to full, suggesting they're getting 12v. The voltage regulator in the fuel gauge must have blew or something as soon after the fuel gauge stopped working at all and the oil and temp gauges underreported. I've had the gauges sent to be repaired and since then they all three now underreport. The ammeter has continued to do this throughout and does it with the right side dash circuit board disconnected, so it's probably not the fuel gauge.
I put in a new voltage regulator from Classic Industries several months ago. There wasn't any signs the previous one was malfunctioning and I still have it, I just replaced it anticipating problems. MD2439 - 1961-69 Mopar A & B-Body Voltage Regulator
I suspect a short somewhere but am not sure. Anyone have any leads on what's going on or how to better diagnose it?

See video
 
doug 371 said:
maybe it's the voltage limiter for the guages
Click to expand...
That was my thought, but I had them all including the fuel gauge sent in and repaired and it still does this. Rallye dashes have the limiter built into the fuel gauge. It also does it when I have the entire cluster disconnected at the circuit board.
 
Have you check the bulkhead connections to be sure they are clean and tight?
you have a loose or dirty connection somewhere. Also look at your voltage regulator connections as well.
 
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cudascott said:
Have check the bulkhead connections to be sure they are clean and tight?
you have a loose or dirty connection somewhere.
Click to expand...
Hmm, another issue that may be related is that the right turn signal indicator on the hood and in the dash is dimly lit constantly with the turn signals off. It operates normally when signaling a right turn. Possibly related?
I've also recently replaced the turn signal assembly in the steering wheel including the wiring to the connector under the dash. I don't think I botched the wiring but it's something else to check.
 
Traxfish said:
I've got an electrical issue with my 1968 Barracuda. The Ammeter will drop, wave for a second, then return to normal and it does this cyclically. There is an audible click every time it drops and every time it resets. Headlights dim with the waving.
Click to expand...

The ammeter in the video is showing battery charging.
Assuming nothing is miswired, two possibilities:
1. Battery needs charging.
2. Battery doesn't need charging but the alternator is offering power at high voltage. Result is overcharging.

Check the voltage at the battery while the engine is running and ammeter is showing charging.
It should be between 13.9 - 14.9 Volts.
If its over 15 Volts, then check the voltage in the ignition circuit connection to the voltage regulator.

That will get you started on diagnosing.

Traxfish said:
There is an audible click every time it drops and every time it resets.
Click to expand...
I noticed that in the video. It makes no sense as far as the gage goes. The ammeter needle movement is trom the magnetic field created by the current going around it.
Will need to think about that.

Traxfish said:
The gauges at the time were overreporting, going strait to full, suggesting they're getting 12v. The voltage regulator in the fuel gauge must have blew or something as soon after the fuel gauge stopped working at all and the oil and temp gauges underreported. I've had the gauges sent to be repaired and since then they all three now underreport.
Click to expand...
It would have been easier to test on the bench but can do some testing on the car depending on what you can scrounge up.

However I am a bit confused because in the video the gages are all pegged!
 
The causes of this are "in no order"
Bad connections in the harness and grounds
VR if it is the old electro-mechanical type
Sometimes the battery but very rare

You need to go clear through the heavy ammeter/ charging circuit. Refer to the diagram in the MAD article. The connections at battery, starter relay, fuse link, bulkhead connector, ammeter, possibly (but rare) the welded splice), The VR field connections and the path back to the key and through the ignition switch and to it's sourse including CONNECTORS (terminals) and the VR GROUND.
 
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Mattax said:
The ammeter in the video is showing battery charging.
Assuming nothing is miswired, two possibilities:
1. Battery needs charging.
2. Battery doesn't need charging but the alternator is offering power at high voltage. Result is overcharging.

Check the voltage at the battery while the engine is running and ammeter is showing charging.
It should be between 13.9 - 14.9 Volts.
If its over 15 Volts, then check the voltage in the ignition circuit connection to the voltage regulator.

That will get you started on diagnosing.


I noticed that in the video. It makes no sense as far as the gage goes. The ammeter needle movement is trom the magnetic field created by the current going around it.
Will need to think about that.


It would have been easier to test on the bench but can do some testing on the car depending on what you can scrounge up.

However I am a bit confused because in the video the gages are all pegged!
Click to expand...

Battery reads a steady voltage in normal range (~13.5-14 volts charging).

Do you mean current going through other circuits causing magnetic field and interfering with the ammeter? That still sounds like a problem.

I have a previous thread talking about the gauge problems. There you did share guides on how to bench test and repair gauges including the limiter in the fuel gauge, but I opted to send them to a gauge specialist because I was nervous about trying to open them myself. At the time the voltage limiter was failing and that's why they are all pegged. This video was taken before I sent in the gauges to be repaired and put it all back together, but the behavior with the ammeter continues..
 
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Traxfish said:
Battery reads a steady voltage in normal range (~13.5-14 volts charging).
Click to expand...
So the next question is whether the battery is fully charged.
It's possible the's a bad/loose plate in the battery, but the clicking sounds like its right there inthe dash.
Charge it up on a charger and see what the charger indicates while doing so.
 
Mattax said:
So the next question is whether the battery is fully charged.
It's possible the's a bad/loose plate in the battery, but the clicking sounds like its right there inthe dash.
Charge it up on a charger and see what the charger indicates while doing so.
Click to expand...

This was just after a cold start after sitting for a while, and I didn't have the charger on it, so it was probably just charging. I can try putting the battery on the charger.
 
Do you mean current going through other circuits causing magnetic field and interfering with the ammeter? That still sounds like a problem.
Click to expand...
No. The ammeter needle is movement is caused by the current going to or from the battery.
Lemme find a photo.

Here's the back view,

upload_2019-5-26_14-32-20-png-png.png

The metal plate carries the current around the pivot of the needle and creates a magnetic field.
 
Any accessories grabbing power at battery or starter relay post?
 
crackedback said:
Any accessories grabbing power at battery or starter relay post?
Click to expand...
I've not added anything to the car that draws power. Electrical system should be completely stock.
I can check if one of the circuits are drawing over the fuses. I recall reading there's a way to isolate shorts that way.
 
On my 68 Barracuda with the Rally Cluster there is a separate plug-in VR for the gauges. I know this because I took it out and subbed in an Electronic one that I built from instructions in a magazine article, that has a constant 5volts output; so there is no more wandering of the needles . IDK, yours may be different.
Hang on a sec, I just remembered something, my dash is not a 68. I think it is out of a 70 Duster.
In any case, the Ammeter is on a separate and isolated circuit;
To one side of the gauge, comes battery voltage.
To the other side comes alternator output.
Whichever voltage is higher, pushes the needle in that direction.
------------------------------
With the engine OFF, and the Key in RUN;
obviously, the alternator is not putting out. The needle should be just a lil to the discharge side, showing that the ignition system is still on-line.
If you now have something clicking under the dash, loud enough to hear, and you have proved it is NOT the gauge-VR (which they are extremely quiet), about the only thing it can be is the signal-light flasher.
The flasher, in Neutral should not be drawing current....... unless the flasher switch wiring in the signal-switch or it's circuit, is shorted up under the steering wheel or in the column. This would put a load on the circuit and the ammeter is just doing what ammeters do, responding to it.
So then, unplug the flasher, and all your troubles should disappear. Well just until you realize ... what do I do now, lol. If that sorts it out, the next stop is to prove the Flasher is correct for your car, and if it is,
then remove the steering wheel and inspect the signal switch and or it's wiring.
There is a big connector down at the bottom of the column. I have seen that connector overheated and contacts connected to things that they shouldn't be.
I have also seen the contacts in the signal switch overheated and the plastic/nylon body all melted.
If your signal switch is in fact melted, the aftermarket ones are rather hit and miss as to quality and durability. I rob other OEM columns for the factory parts I need.

Now before you tear your hair out, and before you do anything;
remove all your signal bulbs. If the problem goes away, inspect your bulbs for shorted filaments.
With the Signal sw. in Neutral, these should NOT affect the circuit. But, if the Brake-lite is simultaneously on, that power can back-feed the Signal switch thru the shorted filament, and it drove me crazy, looking for it.
 
Last edited:
AJ/FormS said:
On my 68 Barracuda with the Rally Cluster there is a separate plug-in VR for the gauges. I know this because I took it out and subbed in an Electronic one that I built from instructions in a magazine article, that has a constant 5volts output; so there is no more wandering of the needles .
The Ammeter is on a separate and isolated circuit.
To one side of the gauge, comes battery voltage.
To the other side comes alternator output.
Whichever voltage is higher, pushes the needle in that direction.
------------------------------
With the engine OFF, and the Key in RUN;
obviously, the alternator is not putting out. The needle should be just a lil to the discharge side, showing that the ignition system is still on-line.
If you now have something clicking under the dash, loud enough to hear, and you have proved it is NOT the gauge-VR (which they are extremely quiet), about the only thing it can be is the signal-light flasher.
The flasher, in Neutral should not be drawing current....... unless the flasher switch wiring in the signal-switch or it's circuit, is shorted up under the steering wheel or in the column. This would put a load on the circuit and the ammeter is just doing what ammeters do, responding to it.
So then, unplug the flasher, and all your troubles should disappear. Well just until you realize ... what do I do now, lol. If that sorts it out, the next stop is to prove the Flasher is correct for your car, and if it is, then remove the steering wheel and inspect the signal switch and or it's wiring.
There is a big connector down at the bottom of the column. I have seen that connector overheated and contacts connected to things that they shouldn't be.
I have also seen the contacts in the signal switch overheated and the plastic/nylon body all melted.
If your signal switch is in fact melted, the aftermarket ones are rather hit and miss as to quality and durability. I rob other OEM columns for the factory parts I need.
Click to expand...
I think you're narrowing it here. The original switch had a broken cam so I replaced it with one from classic industries, including the wiring down to the connector. I was immediately disappointed in it as the new cams are just a bit too wide to be hit by the cancel pin in the steering wheel, so the turn signals don't auto cancel at all any more.
 
Well, ran some tests.

Pulled the steering wheel and inspected the switch, switch is fine.

Disconnected both the switch connector and the flasher, Ammeter still did the wave with ignition in both ACC and ON. Found a broken wire on the switch cables after the disconnect. The orange wire to the gear selector light. My wiring was shoddy on that one as I had limited wire and it already had splices in it and moving it around separated the wire in the crimped splice. That isn't the problem, but it is a problem.

The round fender light on drivers side wasn't working. Works on passenger side. Disconnected it to isolate it and the ammeter still did the wave in both ACC and ON. Possibly a short in the line before the bulb?

Tried it with lights on and off, still had the issue. Turning on the lights dipped the ammeter well into the discharge side and still did the wave in both ACC and ON.

I put the charger on the battery. It's currently reading 13v and 1.25a.
 
Traxfish said:
Well, ran some tests.

Pulled the steering wheel and inspected the switch, switch is fine.

Disconnected both the switch connector and the flasher, Ammeter still did the wave with ignition in both ACC and ON. Found a broken wire on the switch cables after the disconnect. The orange wire to the gear selector light. My wiring was shoddy on that one as I had limited wire and it already had splices in it and moving it around separated the wire in the crimped splice. That isn't the problem, but it is a problem.

The round fender light on drivers side wasn't working. Works on passenger side. Disconnected it to isolate it and the ammeter still did the wave in both ACC and ON. Possibly a short in the line before the bulb?

Tried it with lights on and off, still had the issue. Turning on the lights dipped the ammeter well into the discharge side and still did the wave in both ACC and ON.

I put the charger on the battery. It's currently reading 13v and 1.25a.
Click to expand...
Is that an automatic digital charger? If so, let it do its thing.
Still 1.25 amps at 13 Volts is a fairly slow charge. I don't know what that might go up to at 14 Volts, but not 20 amps. A couple years ago I hooked a low battery up to manually controlled charger. At 14 volts the battery was sucking 30 amps. Changed the setting so the battery was seeing 13.3 volts and the battery was sucking about 9 amps.

Lights on - should see about 12 amps discharging, key off.
Lights on with key in access and should see about 14 amps discharge - steady.
The extra amps are going through the points and coil, or ECU and coil, and maybe the alt roter - so don't do this for a long time it will heat the coil.
The ammeter scale is roughly 40 amps discharge to 40 amps charge.

The turn signals are only hot with the key in run or accessory.
The headlights and side markers and brake lights are always hot.
 
Traxfish said:
Ammeter still did the wave with ignition in both ACC and ON.
Click to expand...
With key in Accessory, the run circuit can be eliminated. Dana's tested that here 67-69 Dart Ignition Switch Pinout
But it makes sense. Otherwise why have an accsory postion on the switch.

Since it doesn't happen with the key off, that eliminates the main circuits that are always hot.
upload_2022-9-9_20-43-48.png

Besides the turn signal flasher, on the switched accessory circuit there's the wiper switch, and from the fuse box the heater blower, and radio circuits.
 
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they all do that from time to time
its a combination of battery on the edge of being fully charged or to put it another way voltage seen by the regulator from battery, regardless of its state of charge is bang on the switching point between charge and do not charge.

charge current comes through ammeter on standard car so you see it twitch with every on off on

The regulator is switching alternator off and on becasue it can't make up its mind what to do.

Temperature has an impact on how well a battery takes charge and to the regulator which in a modern one uses a fine balance of volatge across a small circuit to switch a power transistor off and on to provide 0-5 v into the field
it can't be half off or half on so it just flip flops
some times on the on off switch point can change with ambient temperature.

take it for a drive, get battery well charged and it will stop

problem can be made worse by the regulator not being able to see battery volatge or by being badly grounded which means it can't work out what the battery voltage is, by compariosn with ground ov
i.e loose on its mountings or they have corroded

in both cases check wires and mounting, bad connection at battery or between battery wire and the clamp can cause problems.

Dave
 
Dave999 said:
they all do that from time to time
its a combination of battery on the edge of being fully charged or to put it another way voltage seen by the regulator from battery, regardless of its state of charge is bang on the switching point between charge and do not charge.

charge current comes through ammeter on standard car so you see it twitch with every on off on

The regulator is switching alternator off and on becasue it can't make up its mind what to do.

Temperature has an impact on how well a battery takes charge and to the regulator which in a modern one uses a fine balance of volatge across a small circuit to switch a power transistor off and on to provide 0-5 v into the field
it can't be half off or half on so it just flip flops
some times on the on off switch point can change with ambient temperature.

take it for a drive, get battery well charged and it will stop

problem can be made worse by the regulator not being able to see battery volatge or by being badly grounded which means it can't work out what the battery voltage is, by compariosn with ground ov
i.e loose on its mountings or they have corroded

in both cases check wires and mounting, bad connection at battery or between battery wire and the clamp can cause problems.

Dave
Click to expand...
Thanks, this is very helpful.
The regulator is new from classic industries. It says it's electronic, instead of mechanical, so I don't know if that enters into the conclusion. I still have the previous one and I didn't think it was malfunctioning when I replaced it. I am open to the idea that the new regulator was bad or didn't work well out of the factory.
The battery was replaced recently too. I accidentally drained the previous one completely leaving the car on when I shut the engine off at the ballast resister while working on it and forgot to turn ignition off. Could that have also damaged the regulator?
The battery wires are frayed a bit at the connections. That could be something to look at. New ones are not cheap though. I can also check the connections at the regulator to make sure something didn't wiggle loose when installing.
Is a problem with the alternator causing rapid turn on/off by the regulator a possibility? I've suspected the alternator is going bad, mostly due to engine bay noise when running.
I've left it on the charger for the past few days which reads 100% now. I could test if it's alternating on and off now.
 
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