68 Charger Volt/Ammeter gauge issue

[stushug]

I just had the car out, and I noticed that the ammeter was pegged all the way to the right. This happened about a month ago also, but the next time I drove the car it was fine. When I got home, I put the headlights and high beams on to draw some current. At idle the lights were a tiny bit dimmer than when I revved the engine, which I would consider normal. My problem is, the gauge is staying pegged all the way to the right no matter what. The cluster was completely redone and whatever updates they normally do were applied to make it work with the newer electrical systems. What would be causing the gauge to act like this, when the charging system is working properly? I also noticed that the gauge stays pegged even after the key is turned off. I can't remember if it used to return to the center when the key turns off. The battery is only a year old and is fully charged.

 

[pnora]

Was it a voltmeter conversion? Did you check the charging rate with a voltmeter? If it is ok 14 volts aprox. the gauge must be bad whether its an ammeter or voltmeter.

 

[stushug]

Was it a voltmeter conversion? Did you check the charging rate with a voltmeter? If it is ok 14 volts aprox. the gauge must be bad whether its an ammeter or voltmeter.

I don't remember what the conversion was. When the gauge was working, (it's been fine for the last 12 years) it would normally sit just to the right of center when the car was running. I didn't have a chance to check the charging rate yet, I'll do that tomorrow and post the results.

 

[Nacho-RT74]

The ammeter gets the needle attached to the magnetic counterweight which moves with the current going throught by friction. Needle could get moved. Is REALLY weird this could happen with original gauges at least, but there is a chance. Will need to remove the gauge and relocate the needle aligned to the counterweigh.

somebody around got a similar problem with a repro ammeter. But he didn’t take care about get it “realigned“ so installed back the original one. Is your ammeter a repro unit?

And yes, with engine turned off and nothing working, it should rest in center. When you open the door and dome light turns on, should show some small discharge thought.

 

[stushug]

From what I remember, the gauge is still set to operate as an ammeter, not a voltmeter. As far as I know it is the original gauge to the car. Everything else is original, so I'm pretty sure this is original too.

 

[1968rt]

You might want to consider a bypass. Dash fires are common. Catalog

 

[Nacho-RT74]

When everything is off voltimeters needle rests on left side of scale while ammeters needle rest in the middle of the reading scale.

 

[72RoadrunnerGTX]

Dash fires are common. Catalog

Really? Do tell.

 

[pnora]

You might want to consider a bypass. Dash fires are common. Catalog

They absolutely are. Those ammeters and old wiring, connections, bulkheads are just inviting failure esp. when adding high draw accessories.

 

[72RoadrunnerGTX]

Dash fires are not common with well maintained, properly loaded stock Chrysler charging systems. Original bulkhead connector failures are common, always have been. Any electrical circuit can burn, no matter the age, if neglected, abused, or operated outside of its design load limits. There are many past threads here on this supposed “spontaneously combusting ammeter” non-issue. If you must refer to the “Mad Electrical” article, read carefully about what specific platform it is addressing, late seventies truck plastic framed ammeters.

As for this thread’s questions, need to verify the ammeter is still in place, then troubleshoot the ammeters overcharging indication, make sure there are no loads added to the battery side of the ammeter (no added loads directly connected to the battery or starter relay). Any loads on the battery side of the ammeter will register as false charging current while in operation and place the entire charging system wiring/connections outside of the original designed current limits (this causes connection heat related damage). All vehicle loads need to be on the alternator side of the ammeter, as are all factory loads.

 

[Nacho-RT74]

 

[stushug]

The whole gauge cluster was rebuilt in about 2007 by John Wolf and re-installed in 2009 with ALL new wiring throughout the car when the car was restored. Nothing has been touched since then. The gauge working working correctly until yesterday, then it wasn't.

As for this thread’s questions, need to verify the ammeter is still in place, then troubleshoot the ammeters overcharging indication, make sure there are no loads added to the battery side of the ammeter (no added loads directly connected to the battery or starter relay).

Not sure what you mean when you say verify that the ammeter is still in place.

 

[72RoadrunnerGTX]

Understood there was a possibility the ammeter had been converted to a voltmeter, rereading the OP, sounds like you are sure it was not converted. Also noticed you said the ammeter was pegged with the key off, that would indicate a mechanical issue with the ammeter. I would disconnect the battery to verify it’s not actually registering any current flow. Would also inspect the ammeter connections carefully, loose connections can lead to excessive heat build-up at the ammeter terminals that can distort the internal bus bar enough to cause a sticking movement.

 

[pnora]

Dash fires are not common with well maintained, properly loaded stock Chrysler charging systems. Original bulkhead connector failures are common, always have been. Any electrical circuit can burn, no matter the age, if neglected, abused, or operated outside of its design load limits. There are many past threads here on this supposed “spontaneously combusting ammeter” non-issue. If you must refer to the “Mad Electrical” article, read carefully about what specific platform it is addressing, late seventies truck plastic framed ammeters.

As for this thread’s questions, need to verify the ammeter is still in place, then troubleshoot the ammeters overcharging indication, make sure there are no loads added to the battery side of the ammeter (no added loads directly connected to the battery or starter relay). Any loads on the battery side of the ammeter will register as false charging current while in operation and place the entire charging system wiring/connections outside of the original designed current limits (this causes connection heat related damage). All vehicle loads need to be on the alternator side of the ammeter, as are all factory loads.

In a perfect world with correct loads there is little problems. I can tell by your post you never worked in a dealership back in the day. Working in a dealership since 1972 I can tell you I fixed many. Some did not get fixed [imagine that and why]. For what its worth plastic or steel cluster frames they still had ammeter meltdowns. As said poster needs to find out and fix what is going on with his car.

 

[beanhead]

IMO everyone should have a clamp-style (or U-style, like the Fluke T-600/1000) multimeter so current can be measured without having to de-terminate wires and put the meter leads in line with the circuit.
The first thing (I) would do is take a current reading under the dash when the needle goes to full...that will tell me if the problem is real, or if it's just the gauge going titsup.
Unless the ammeter gauge really has gone bad, the needle should NEVER go to and stay at full charge, this indicates a high-current (bad!) situation....find and fix ASAP or you will eventually have a meltdown, or worse. Best case scenario the fusible link opens and saves you, but I wouldn't bet my Mopar on it..

 

[72RoadrunnerGTX]

In a perfect world with correct loads there is little problems. I can tell by your post you never worked in a dealership back in the day. Working in a dealership since 1972 I can tell you I fixed many. Some did not get fixed [imagine that and why]. For what its worth plastic or steel cluster frames they still had ammeter meltdowns. As said poster needs to find out and fix what is going on with his car.

You know, I think you and I have had this discussion before, post #34 here. I've been working at automotive dealers since I was 19, we've had quite a different experience working at Chrysler dealers back in the day it sounds like. I never saw any ammeter connection issues that was not directly related to an improper previous servicing or incorrect loading.

 

[stushug]

I just checked the car. It had been sitting, ignition off since last night. The gauge was still pegged at +40. I disconnected the battery(both terminals) and the gauge did not move. I checked the battery and it measured 13.11V. I reconnected the battery cables and started the car. While running, I checked the voltage (at the battery terminals) and got 14.08 volts just above idle. That tells me the charging system is working properly and it is most likely the gauge has failed. What do you guys think? The picture was taken with the key OFF.

 

[pnora]

I just checked the car. It had been sitting, ignition off since last night. The gauge was still pegged at +40. I disconnected the battery(both terminals) and the gauge did not move. I checked the battery and it measured 13.11V. I reconnected the battery cables and started the car. While running, I checked the voltage (at the battery terminals) and got 14.08 volts just above idle. That tells me the charging system is working properly and it is most likely the gauge has failed. What do you guys think? The picture was taken with the key OFF.

View attachment 1504677

Failed gauge.

 

[pnora]

You know, I think you and I have had this discussion before, post #34 here. I've been working at automotive dealers since I was 19, we've had quite a different experience working at Chrysler dealers back in the day it sounds like. I never saw any ammeter connection issues that was not directly related to an improper previous servicing or incorrect loading.

We did. I read the post and we can agree on one thing for sure. Bypass and run a voltmeter.

 

[pnora]

I just checked the car. It had been sitting, ignition off since last night. The gauge was still pegged at +40. I disconnected the battery(both terminals) and the gauge did not move. I checked the battery and it measured 13.11V. I reconnected the battery cables and started the car. While running, I checked the voltage (at the battery terminals) and got 14.08 volts just above idle. That tells me the charging system is working properly and it is most likely the gauge has failed. What do you guys think? The picture was taken with the key OFF.

View attachment 1504677

Do your self a favor and find a replacement voltmeter instead of an ammeter and by pass it completely. You could send your out for a conversion. This is what mine looked like after conversion.