Erratic Ammeter Behavior – Seeking Advice

[RM21H9-SunfireYellow]

Last night, after driving for about an hour, my ammeter gauge started acting erratically. For context:

• I drove during daylight for an hour with no issues.
• Parked for about an hour.
• When I left, it was dark, so I turned on the headlights and drove off.

About 20–30 minutes into the nighttime drive, the ammeter began jumping back and forth—then settled briefly—then started again. While this was happening, the instrument cluster lights flickered in sync with the gauge: dimming during discharge and brightening during charge.

I made it home and checked the wiring around the alternator and bulkhead. Everything looked okay, but clearly something’s off.

Any ideas on what could be causing this? I’d really appreciate any guidance or suggestions.

 

[72RoadRunnerGTX]

An all stock ’69 electrical system? I’d be focused on troubleshooting the voltage regulator with the described symptoms.

 

[cshd9199]

Bad Ground ? you can't have enough I run 3 core support , firewall , engine. Also I am running a 130 ALT (tuff stuff ) and a matching REG

Tuff Stuff Performance 7524 Alternator Replacement Voltage Regulator amazon​

 

[V.R.D]

the amp meter in the dash is getting hot look under the dash and you will see if the wires are loose or is the insulator broken and shorting out . REMOVE THE NEGATIVE BATTERY CABLE so not to burn down the car

i hope im wrong and it is the regulator as said above and yes check the ground from the engine to battery and the engine to body ground cable are clean and no paint or rusted clean.

 

[JRs Road Runner]

Had the same problem in my 70 challenger it was bad connection at amp gauge.

 

[RM21H9-SunfireYellow]

Well, I found out the hard way. Short answer: The alternator failed. I checked all the wiring connections at the alternator, but nothing appeared suspicious. I also checked the wires on the ammeter; they were good, and the ammeter didn't feel warm or hot to the touch. So I went for a test drive, everything was running good. Then the ammeter started acting erratically, the engine started to die, there was a loud backfire, and then the car went dark. Lucky for me, the fuseable link worked. The link burned, and the bulkhead connector melted a bit. After this happened, I checked the wiring again, and I found the charge post on the alternator was loose. The wire is tight to the post, but the whole post is loose. This wiring is original, which means it is time to replace all of it from bumper to bumper. I know there are factory replacement kits out there. Now I need to find the right one for this car.

Thank you all for your ideas & suggestions.