‘75 Dart Sport Charging system issue(s)

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Jax_1975_Dart

Jax_1975_Dart

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I have a ‘75 Dart Sport with a 225 /6. Everything is stock (as far as I know). Long story short: I noticed my battery dies every few days and requires trickle charging to maintain it. Now that I finally have the car at my home.. I was able to multimeter the battery terminals. It’s around 12.2 V at rest and 12.19 while running. This leads me to believe the alternator’s power surplus is not properly routing back to the battery.

I was poking around (looking for where the VR is mounted) and stumbled across these disconnected electrical connectors. Could this possibly be related to my no charge woes?

JPGi3BX.jpg



GQcBfMT.jpg
 
Your voltage regulator is right there in the pic bolted to the RH inner fender. The plug your showing is from an old emissions control system that's been discarded
 
moparmat2000 said:
Your voltage regulator is right there in the pic bolted to the RH inner fender. The plug your showing is from an old emissions control system that's been discarded
Click to expand...

Thank you! I’ll follow a fellow board member’s (67dart273’s) suggestions for probing the ballast IGN to Voltage regulator ground. This should help me to pin point if it’s the VR or alternator.

I mostly wasn’t sure what the white connectors were for.
 
Some quick checks. With the engine running on fast idle, measure voltage at alternator stud. If it is near same as battery, and down below 13+V it is not charging

If it is 'way high' 15-16V and the battery is still low, then you have a break in the charging path from alternator to battery. I believe (you will have to look) that those cars have a big white connector that separates the engine harness from the firewall. Those connectors are flaky. Otherwise, the bulkhead connector or ammetr are suspect

If the alternator is low, try this

With key in "run" but engine stopped, "backprobe" the alternator field terminal with the blue wire. If you need better access switch them around. You should have nearly same as battery at the blue. If you do, remove the green and jumper that alternator terminal to ground. Start engine, bring up RPM see if ammeter shows charge or voltmeter increases. Don't allow it much above 15-16V

If it comes up to that, move on. If not, check brushes, etc, and troubleshoot alternator or replace

If alternator charged in test above, now reconnect field wire(s) and disconnect VR connector. Look at connector with a light for corrosion, work in on/ off the VR several times to scrub connection. Make CERTAIN VR is grounded.

"Rig" a way to jumper across the two VR terminals in the harness connector. Again see if it will charge. If so, replace VR
 
It’s been raining non stop and Eta come through recently... haven’t been able to do much with the Dart but, changed out the voltage regulator (on a whim that it might be the problem) and it’s not. A new VR installed and still no additional volts when tested at the battery terminals with a multimeter.

Is there supposed to be a wire (or wires) plugged into the alternator stud? I see a nut, washer and nut on the rear bolt but, no wires connected to it. I couldn’t get a good picture but, below is the stud I’m referring to. I also pulled off and wire brush cleaned the green and blue connectors on the back side of the alternator.



I’ll try the alternator stud test first tomorrow afternoon - weather permitting.

Car fires right up and drives great but, have to charge battery with external C-Tek maintainer/tender.

Thanks!
 
I cannot see in your photo WTF you have. The alternator stud should have batttery voltage on it at all times. Be CAREFUL. That is a high current circuit and IS NOT fused except for the main fuse link, which is poor protection

Please stop throwing money at parts and make a few tests. I attempted to give you some suggestions. If you do not understand them we can go through a step by step. There are some simple things you can do. You do need a meter, and possibly some alligator jumper wires.

Also examing the harness up near the firewall, looking for a WHITE (or creme) colored connector. Some cars had these which separates the engine harness from the firewall. That connector is a problem
 
Sorry for the terrible pic. Was hastily taken in between the rainstorms.

Is there supposed to be any wires connected (at all) to the alternator terminal output stud?
 
Here’s a shot of my ‘75 Scamp engine bay. It’s a 318 but that plug on the passenger side fender you show in your first post should be unplugged (as is mine).
FD5895CB-417C-47C9-B6CA-4253C58DABAD.jpeg
 
Yes, there should be a rather large gauge wire connected to the alternator output terminal. That is why you’re charging the battery with a trickle charger, the alternator cannot charge the battery if it’s not connected.
 
mopardude62 said:
Yes, there should be a rather large gauge wire connected to the alternator output terminal. That is why you’re charging the battery with a trickle charger, the alternator cannot charge the battery if it’s not connected.
Click to expand...

LOL I posted earlier:

"The alternator stud should have batttery voltage on it at all times. Be CAREFUL. That is a high current circuit and IS NOT fused except for the main fuse link, which is poor protection"

I guess I thought that answer should be obvious. YES big wire and YES dangerous if you are not careful Disconnet battery before screwing with this
 
Update: I’m a moron and somehow overlooked the super obvious alternator terminal stud that is clearly plugged into a black cap/connector near the top. There’s a smaller posterior terminal stud at the bottom (that I mistakenly thought was the main terminal stud) with no wires connected...

Current status: Battery not receiving charge. Starting to think there’s trouble in between the alternator and battery. I probed the alternator stud (while engine warm) and readings were way high 18.5+ V. Reading at battery (while running) is less than 12.5V.

First pic is alternator reading. 2nd battery while running.
 
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You are CORRECT. Start by testing the continuity from the eyelet terminal at the alternator to the black wire. They can break inside

Read this article about the problems with Mopar bulkhead connectors and ammeters

Catalog

which explains the problem and also has this nice, simplified diagram of power distribution:

amp-ga18.jpg


Follow along: Power output from the alternator goes from the output stud on big BLACK through the BULKHEAD CONNECTOR, under the dash to the WELDED SPLICE....to and through the AMMETER...out on the big RED wire and back out the BULKHEAD CONNECTOR .. through the FUSE LINK....to the BATTERY

SInce the car accessories seem to work?? and the car runs, the fuse link/ RED/ bulkhead connector for the RED are likely if not "OK" then at least functioning.

So I see the problem as likely something in the BLACK output wire or the BULKHEAD CONNECTOR for the BLACK wire


First three things I'd check:

1....Continuity from alternator output eyelet terminal to the wire itself
2...Follow the harness and look for a LARGE WHITE connector. This was used on some years and is a big problem. It separates the engine from the firewall
3....Take the bulkhead connector apart and inspect those terminals.
 
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I recently had charging system problems myself. I had a bad alternator and I replaced both Alt and VR at the same time and ran into more problems. I should've just attacked one thing at a time to rule out individual pieces of the puzzle. Anyway my problem ended up being the Napa VR I had gotten was bad right out of the box. The wires inside the had come apart and would make periodic contact causing all sorts of problems.

Good luck!
 
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