Dealing with some charging issues on my 71 Challenger. Mopar Electronic ignition with newer harness. I am running a square back 65 amp alt.

Recently I was driving and the AMP gauge was jumping all over. I found a loose terminal for one of the field wires so I tightened that thinking it was a connection problem. I went out for a drive and about 20 mins in it started showing a high charge. I had the alternator rebuilt and it has the same exact symptom (charge showing high on gauge). Thinking that I fried the Mopar VR, I swapped in a NAPA piece and it did not fix the problem.

I am going to go through and make sure I have good firewall ground (the VR is grounded just fine from what I can tell). I suppose my firewall bulkhead connections could have corroded over time so I will check those as well.

My question is this: Is there anything that could go wrong at the AMP gauge itself that would cause this symptom? I can't check the voltage while driving across the battery terminals to my knowledge. This car has always dipped really low when using the headlights and turn signals (even with an electronic flasher relay). I assume it is not the gauge voltage limiter since the AMP reading is full power, not switched.

Thank you for the brainstorm. I checked old threads but didn't quite get the needed info.

Well, you spent a lot of money for nothing so far.

Do you have any add on loads (stereo, electric fuel pump, etc) wired directly to the battery?

That would show a charge on the system.

Read the MAD electrical page, then check the entire charging circuit.
Yes, the amp gauge (and connections!) can can issues.
Then search you tube for Voltage drop testing and see what the voltage is at each point between the alternator and the battery in the driveway with the lights, heater and radio on.

Thanks Rod. I am going MAD; worked well in the truck. Appreciated.

Going crazy with this. I want to upgrade to a voltage gauge but I am thinking that the amp gauge is telling me something, so before I phase it out I'd like to solve it.

Added 2 grounds to the block with one at the mopar regulator. I replaced the regulator with an nos one. I had the exact same problem. I got to thinking that the alt was bad after this so I swapped in an extra. Got in and it was running perfect. Rode around the block and halfway the amp gauge started jumping up with the rims.

Cranked it to test again and it spun when I let off the key so I swapped the ballast. Same issue.

I am stumped. How can it read fine for a bit and then go back to being faulty? Same thing happened when i swapped a regulator out a while back....... Fine for a bit and back to jumping.

Can the amp gauge be bad but only read sometimes?

Volts at battery didn't go over 13.7 but amps are different. Maybe I don't get it.....

rebuilt alt/new reg & we can assume (for now) that they are OK & it is a wiring prob. I would pull the 2 field leads from the alt and the triangle connector from the reg & with jumper wires run 12V to one of the alt field terminals and to the top terminal at the reg triangle (both are the blue wire circuit) then jumper wire connect the other alt field terminal to the side reg terminal & wouldn't hurt to jumper the alt case and the reg case both to the batt neg & fire it up & see if it straightens out. If not I'm thinking the rebuilt alt is bad but one thing at a time. You might visual the brushes/brush holders for anything out of place

bought one of the NEWER harness also first the fusablie link was not connected properly,i would turn a corner and the car would die,then had one of my turn signals stop working again NEWER HARNESS,one of the wires was not crimped good slid right out had to open the plastic housing and recrimp the wire,seems they repo harness are not made very well,also had a charging issue went with a new alternater with a smaller pulley to spin more at idle and in gear solved the discharge problem

Thanks Robert. I will jump around to see...... Just seems wierd that it isn't constant. Could be a crimp it suppose too.

reportedly some digital voltmeters are hard to get the numbers to settle down but if the amp gauge is swinging wildly then that definitely needs to be addressed/taken care of before considering an upgrades. We'll solve it & go from there. The MADD info is good if you don't mind losing your ammeter function (I do mind). I clean every terminal/connection and add a voltmeter to switched 12V & relay the headlights/heater/ac directly to the alt batt stud with relays & do Nachos bulkhead parallel bypass. the swinging ammeter sure sounds like a bad electromechanical reg or the alt. Keep us posted. Your batt is a good one right? EDIT had an ammeter that would go all the way to charge when I revved the end but came back to near 12 o'clock at idle/lower speed. it was the electronic reg. more info on WHEN it is wildly swinging (how far/which way)

It's crazy. Idles at center drops just below in gear (like it always has) and goes up as you rev it. I just think it is nuts that it was fine for a few minutes after swapping alts and then back to this.

Is it possible to blow the alternator with a problem in the system?

First one was a rebuilt local. The 2nd one I swapped in was a rebuilt one I got from Carlisle (Billy Ware) I have one of his in my truck without issue.

This is the 3rd volt regulator with no change. I will try jumpers and report back.

I use a plug in volt gauge in cig lighter in my challenger.

(1) sounds like classic full fielded reg (when tghe RPM's go up to where the alt can put out enough to peg the ammeter, the (faulty) reg let it do so however you have replaced it several times. (2) not likely in this case but the alt field system could have an improper grounded in the green wire side internally that is full fielding it (check those brushes/brush holders) (3) swap the good alt that is in your truck in & we'll have some answers in less than an hour. I'm thinking I (might) do that before the jumpers unless you have lengths of wire/alligator clips made up/ready to be used. Holler back with any news

Gonna jump with fear that I am wrecking good alts ( if that is possible) I have plenty of wire so I will report back

Could possibly a defective battery send out conflicting signals that might cause these random signals seen via the amp gauge? Possible an intermittent short in the battery that manifests as it warms or cools. A battery test with professional equipment might be in order.

No surprise that I couldn't accomplish much with a 3 yr old helping me in the garage. Will try later this week.

Robert, is the basis to essentially replace the regulator portion of the harness with separate, external wires to full out those splices? What condition does connecting the alt batt stud to the blue field create? I'm trying to understand it. At the moment, I can' t get my head around it.

From searching the site, I see that you've been helping members figure out this very issue. I'm just frustrated that I've been parked all summer.

I have the 71 service manual, so I can also try the regulator test on page 8-27

I do get a small spark when connecting negative battery cable to battery post.....

And thank you see. Will swap batteries to test too.

(1) remove the (2) blue and green field wires from the alt and (2) pulling the triangle connector from the reg then (3) run 12V from batt pos post or starter relay batt stud to (3A) either of the male alt field terminals and (3B) to the top male nub in the reg triangle and (4) run a seperate jumper (only) from the other male alt field terminal to the "side" terminal in the reg triangle connector. Do nothing with the alt "batt" stud. Jumper the alt case to the batt neg and jumper the reg case to the batt neg. this takes any and all potential wiring harness dead shorts/loose or bad (wiring) connections out of the equation & only leaves the alt and the reg IF the main charge wire from the alt "batt" stud to/thru the bulkhead/thru ammeter & out back to the battery that there are no loose connections/terminals there in that circuit from alt to battery. check the bulkhead (4 terminals) 1 male/female in and 1 male female out for good contact and the ammeter terminals for tightness (bulkhead is a frequent culprit) and visual on the alt brushes/brush holders. then fire it up at a fast idle with a fully charged batt & see what the ammeter does. Holler back when you can

Had similar problem. When driving and RPM was increasing the ammeter would peg itself and volt meter would read 16 + volts and lights would get SUPER bright.

Tried diff alternators, regulators, checked wiring, bypassed bulkhead connecter and ammeter, nothing.

Finally put on Powermaster 1 wire alternater and no more charging problems. Im sure this just covered up whatever was wrong but its been running like this for 5 years now, no more problems.

was that with the key/eng/all lights etc/everything off or with the engine running? (You dont want to pull a batt cable when the eng is running)