Alternator Gauge issue

[Lazerwolf]

Have a 74 Charger with a 400. Normally alternator needle sets steady about in middle of gauge. Last Friday took it to a local show about 10 miles away. On the way there, needle moved clear over towards C, like it was charging a ton. When I got back, looked for any loose connections but found none. Monday took to a local shop to have it checked about a 1/2 mile away. Needle was wavering slightly near middle but not charging like it was. Shop checked voltage at battery and it was between 14.4 and 14.7, which he said would be normally after just starting it. Battery was in car when I bought it 3 years ago so they checked that. It was down a few amps, 650 amp battery and was something like 590, so he said that was not a problem. Original voltage regulator died last year so that was replaced. Also replaced alternator because one on car when I bought it had back of casing cracked, like it was dropped. Any thoughts? Loose connection in dash? Any help would be appreciated.

 

[miller]

Loose connection in dash?

That is my first thought.

 

[moparedtn]

If the regulator has already passed the test for having a stuck wide open field, next thing to look at is the actual wiring going to the gauge.
The connection at the main harness connector in the firewall is notorious in Mopars for actually melting down to the point of failure - and even fire in drastic cases.
There's been articles published in Mopar mags over the years about how to run the leads to the ammeter by bypassing the main connector all together to get rid of the problem.

 

[Nacho-RT74]

I can't say what exactly is the problem but an advice! Take your time to a nice mantenience on the charging circuit! System is getting weird signals requesting to be checked before a bigger failure

 

[Lazerwolf]

Thanks for the replies and going to dig into it more this weekend. The reason I asked about a loose connection in dash was because I took out dash last winter to have the clock fixed but had several months of no issues.
The question is what could cause a bouncing meter, if the battery, alternator and voltage regulator are all good? Am I down to a loose connection? Visually firewall connection looked good but am little hesitant about taking it about after 40+ years. I've never had a voltage regulator semi work for example, either good or dead, but could try new one of those.

 

[oldbee]

I'm inclined to go with 'nacho' also, usually the other suspects don't revert to good from bad.

 

[Ranger16]

I had a problem with mine last year and long story short, it was loose posts on the ammeter. I removed the wires and bypassed it. That said, my symptoms where different than yours.

 

[Wietse]

You can measure any voltage loss to determine if there is bad connections, this is how i was told and found the problem.

With the engine idling:
-Measure voltage on the battery posts.
-Measure voltage on the "inlet" side of the regulator (driver side connector). So from negative pole on the battery to the connector (+) of the regulator.

The voltage on the regulator should not be more then 0.2 - 0.3 volt lower then from the battery.
If there is a big difference it means there is a lot off losses due to bad connections, because of this the voltage regulator is not seeing the true voltage and commands the alternator to charge more.

After this, you will have to follow the wire from the alternator and check for any loose or corroded connections.
Bulkhead connector is a dangerous one as already mentioned.
But with measuring the voltage difference you have a reference to see if things improve after clean up/retightening connections.

 

[Nacho-RT74]

Actually voltage can run event throught a hair and won't show variation until there is load on the system

 

[Ron H]

When my engine got a new harness the amp gauge was left disconnected and told the same as moparedtn and wietse posted about dangerous fire potential. Saw evidence of serious heat going on in my bulkhead connection so good thing it's not reconnected I assume. As for the weird reading you say you had checked connections; but you could also trace the wiring to ensure it's not defective or making some connections through inadvertent contacts caused by vibration. If you had dash out wiring ight have been jerked around w/o knowing it. Yeah check your bulkhead out as all vintage mopar folks should I gather. My issue now is to figure out what is the best way to wire up the gauge bypassing BH so if there are any tips would like to get advice.

 

[Ron H]

FYI - this is a pic of my bulkhead showing the heat damage that had been going on.

 

[Nacho-RT74]

When my engine got a new harness the amp gauge was left disconnected and told the same as moparedtn and wietse posted about dangerous fire potential. Saw evidence of serious heat going on in my bulkhead connection so good thing it's not reconnected I assume. As for the weird reading you say you had checked connections; but you could also trace the wiring to ensure it's not defective or making some connections through inadvertent contacts caused by vibration. If you had dash out wiring ight have been jerked around w/o knowing it. Yeah check your bulkhead out as all vintage mopar folks should I gather. My issue now is to figure out what is the best way to wire up the gauge bypassing BH so if there are any tips would like to get advice.

http://www.dodgecharger.com/forum/index.php/topic,33574.0/all.html

 

[Nacho-RT74]

Firts, upgrade the alt... then a parallel path to the existant ammeter wires from and to alt/batt.

You can upgrade the wires with a parallel to bulkhead path, but still will get discharge readings on stock rates alts that's why the alt upgrade needs to be firts... find an alt able to feed at least 45-50 amps iddling. That doesn't mean will be putting out constantly 45-50 amps, just that WILL BE ABLE to do it if the car requires it. Your harness and car will be gratefull.

On a healthy stock wiring and bulkhead, non burnt and without a parallel or upgraded path, still an upgraded alt will be helpfull to save the bulkhead and ammeter, believe it or not.

Amperes are not pushed out by the alternator, but pulling in by the car, so you need a source able to provide that. Remember that! When the power source is not able and paths provides restrictions, then the heat all around is the rule as far the car still is demandíng that power... AND THERE IS NOT A WAY TO SAVE THE CAR DEMAND, unless upgrading also the devices one by one.

While the baby is hungry will allways keep sucking the milk, no matter if the mother is able to do it or not! And will cry for it!

 

[Nacho-RT74]

Of course, if paths are already "done" need to fix that first!

 

[miller]

If it's worth anything, I added the parallel wiring on my 64 Ply.
System is 'up-graded' in ways, since my overhauled alternator wound up being an 80 amp, but was told no problem. The alternator would only put out, what the system needed, no more.
Besides the added parallel wiring, and 80 amp alternator, rest of the 64's system is stock. Admit the majority of it was in good shape, including at the firewall block, and the ammeter itself. Yes, it's wired in, and working fine.
A little worried at first, during the 20 minute break-in run, the ammeter pegged full charge. But, halfway through the run, it slowly dropped to center, staying steady there.
All the 'components' are new, battery listed for the car, that's available these days, as far as group.
No extras on the electrical system, but even using headlights...not even a wimper...seems solid. My parallel wire size matches the original 12 gauge wires.

 

[Nacho-RT74]

It's soooo comfortable get that steady centered needle on amm!!!!

 

[Ron H]

I had to upgrade the alt some years back when I installed electronic ignition. As it was I always had the dimming headlights at idle. My question about "parallel" wiring I might assume here bypasses the bulkhead for connecting the gauge? I have unconnected wires with the new harness (two wires on one female a blue and striped green/blue wires) I'm thinking could be for the connection but not sure while I try to study more on this thing. Long story; but the shop I paid premo bucks to rebuild my motor fell short in multiple ways. If anyone can post more detail or a sketch of the wiring for the gauge appreciate it!

 

[Nacho-RT74]

Click on the link on 12th reply

 

[Ron H]

Yes, did that and rough reading but no doubt the guy knows his stuff. Printed out the "This is what we need" diagram to start putting the puzzle together; but diagram shows an entirely different arrangement than my bulkhead so doing some head scratching on it. The shop that installed the harness hasn't got back to me as it would be nice to see what instructions or details might have come with it. First order is to see how the gauge was initially wired to BH under dash and go from there...

 

[Nacho-RT74]

I made the diagrams. Is my text ( sorry, was long time ago and english is not my mother language )

Bulkhead disposition is based on 3rd gen chargers since I have a 74 but color codes are the same on all Mopars. Thicker wires are batt and alt on all, and they are also red and black.

You need just to fix your burnt points and run the extra ones up to ammeter.