Regulator gone bad?

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Wow. You are losing 75% of that between the fuse link & the fuse box.

Hate to see how hot things get with the lights, wipers & heater on. Like 67Dart273 says, there is a welded splice that can cause trouble in that harness.

Put the battery charger on it. Put a couple of shop rags under the wipers, turn on the headlights, wipers & heater. You should be able to find the hot spot with your fingers. 20 watts is a lot of heat.

B.
 
67Dart273 said:
How much of the under-dash harness is original?
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99.9%

If that's OK, then your most probable are the ammeter/ ammeter connectors (which may be jumpered?)

ALSO there is a great big splice in the ammeter/ battery feed circuit IN THE HARNESS. This is a factory "welded" splice, taped up in there that junctions the ammeter, and the hot feed to the fusebox and ignition switch.
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Like I said, the ammeter connections were cut, spliced, and soldered together by me.

I've thought about those factory splices in the harness. I'm really hoping I don't have to tear my custom dash apart in order to rule them out.
 
I've been having the same issues with my 69 dart /6 with a GM 7140 one wire alternator for the last few weeks. I keep coming up with the same exact readings. Now I have more precise spots to check thanks to you. I'll keep watching and post if I find an answer.
 
70Duster440 said:
99.9%



Like I said, the ammeter connections were cut, spliced, and soldered together by me.

I've thought about those factory splices in the harness. I'm really hoping I don't have to tear my custom dash apart in order to rule them out.
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What bohica posted is a good idea, put enough load through the harness that it's drawing some meaningful current, 6-10AMPS, and look and smell for HEAT

Might want to buy/ borrow and infra-red thermometer.
 
Im leaning toward the ignition switch. It has a harness connector that is easily checked but it also has internal contacts that can wear out.
 
Good idea on the IR thermometer - I've got one. Now, if I were only 20 years younger and a foot shorter maybe I could more easily fold myself up under the dash....
 
70Duster440 said:
Good idea on the IR thermometer - I've got one. Now, if I were only 20 years younger and a foot shorter maybe I could more easily fold myself up under the dash....
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If the fault is in the ignition switch contacts you wont see it with a IR thermometer.
 
I ran by where the car is to run a different volt drop test. I don't think the battery was fully charged so I quick charged it for a few minutes.

Fired right up and reved it to verify the alt was working. Then, with it running and the RPM's up I probed the + battery terminal and the dark blue wire terminal at the ballast resistor (Mallory). It indicated a 2.x volt differential! Did the same on the negative side and the difference was millivolts. The ballast resister was hot for only being on a short time.

Can you deduce anthing from this test other than there's an obvious problem?
 
RedFish said:
If the fault is in the ignition switch contacts you wont see it with a IR thermometer.
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I understand that and I may replace it anyway. I know I'm getting a slight voltage drop through the switch but what would be considered normal or acceptable, if any?
 
I wouldn't want any. The is also the amps factor to consider. The very weakest contacts and smallest wire can show 12 volts yet not conduct the amps required to operate everything downstream.
 
70Duster440 said:
I understand that and I may replace it anyway. I know I'm getting a slight voltage drop through the switch but what would be considered normal or acceptable, if any?
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Between the bulkhead loss and the ignition switch, that's the reason I went to relays. The ignition switch still directly switches accessories "for the present"

But ignition, pump, alternator / regulator, and headlights are all on 5 relays, all individually fused.

For me, my own decision. .2V is max drop through the entire path from battery, bulkhead, switch, and back to ignition/ regulator

Any drop in that path ADDS to charging voltage, as essentially your ballast/ regulator terminal is the "sensing voltage" terminal for the system.
 
When will you answer a question, instead of bragging about your car, and (maybe knowledge) ?
 
Thanks for the input, guys.

I'm going to have to take a break from solving the problem and this thread. My father passed away earlier today.
 
70Duster440 said:
Thanks for the input, guys.

I'm going to have to take a break from solving the problem and this thread. My father passed away earlier today.
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I'm very adened to learn of your loss this morning. Prayers sent for you and yours.
 
As I was going through the wiring on my Dart, I found that the alternator wire going into the bulkhead connector was barely holding together. The wire was shredded and falling out of the male connector end. After stripping the wire, cleaning the contacts and soldering the wire and connector, all went back to normal.
 
Thanks for the condolences, guys - I appreciate it. Losing a loved one sucks.

I'm ready to address this problem again. I picked up 3 new male bulkhead connectors (a couple of my old ones were damaged), a fresh fusible link, and a few terminals from Evans Wiring along with a new Airtex/Wells ignition switch. That should help rule out or eliminate some of the weak spots. Going to pull the dash and check the factory splice in the harness while I'm at it too.
 

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Actually, that's what I'm doing. I bought a "Craigslist" "almost new" painless harness and did a sort of partial rewire on my Dart. I picked up a relay control box out of some wrecked Voyager/ minivan and used two of the relays for headlights, one for fuel pump, one for alternator and "future" other, and the remaining for the ignition circuit.

I now have NO measureable drop from battery pos to the regulator

The box had enough "junk" in to fuse all the relays, with just a little rewiring. Don't remember what it's out of, was about 4x4x6 and mounted right on the apron ahead of the washer bottle.

My wiring ain't pretty, but it works.
 
70duster440,

If all your alternator power feeding your system is like factory where it runs from the alternator, thru the bulkhead, thru your ammeter bypass etc. I would completely eliminate the bulkhead with an 8 gauge wire from the alternator to the starter relay post.

Secondly I would eliminate the bulkhead where the main hot feeds into the cabin of the car with another 8 gauge wire (with a 50 amp replaceable fuse at the starter relay post).

Some people just remove the connectors in that bulkhead "channel" and drill out a hole to pass a heavy gauge wire thru (in regards to feeding the main power to the cabin directly off the starter relay positive post).

The alternator should charge directly to the battery in a short run with heavy gauge wire (not thru the bulkhead twice and thru factory wiring). So connecting it to the starter relay positive will be a nice direct route to the battery.

The positive feed (s) to the internal fuse box and ignition switch should feed with a nice heavy wire w/o ancient design small gauge connectors.
Eliminating the anemic bulkhead connectors and anemic wires feeding both the charging, and the main power will eliminate voltage drop considerably.

Additionally you can add a a relay inside the cabin to switch heavy loads rather than having the ignition switch do that work.



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Thanks for the input, Nuker. I did the ammeter bypass years ago when I built the car and I'm familiar with the usual weak spots in the electrical system. The voltage drop, which is primarily occuring somewhere inside the cabin, after the bulkhead, is a recent development. Right now I'd like to pinpoint the source of the problem, if nothing else for my own knowledge, before revamping too many things.
 
Rice, that is basically what I've done. The all knowing, "don't ever argue with me" Dan claims the way around this is to "use a smaller alternator." I say, there's more than one way to skin a cat.

I also say that these bulkhead connectors WERE NEVER big enough. Way, way, WAY back in the '70's I had the optional 60/65? amp alternator on my 70 sixpack car. I had a MINOR amount of amateur radio FM gear in the trunk. This gear, by todays standards, drew very little, certainly less than a modern trunk mount "big" stereo amp. It wasn't long before I was reworking the ammeter circuit.

Back then, I didn't realize that a sixpack car would one day be a millionare's dream, so I just drilled out the bulkhead (yeah, imagine that, and before Al Gore invented the internet) and ran two large ga. wires through there

I also found 3 or 4 other peoples cars in the same boat. Some of these were C barges, with A/C and other accessories, but once "we" learned of the problem, when a guy had charging issues, you learn what to look for.

Another note is that I've found at least 3 vehicles with bad alternator connections. One was a melted ammeter, the others were bad connections/ connectors, all caused the same end result

And, I"ve found 4 cars over the years that had a FAILED WELDED SPLICE in the underdash harness

I can still remember finding my first. My buddies RR had a bouncing ammeter, and "in a parking lot" on a RAINY day, we had the dash cluster out, the wiring pulled out and untaped, and I KNOW he thought I'd never get it all working. But THERE IS WAS. The factory splice was BROKE. A few minutes with a "big iron" was all ti took, taped 'er up, and he was semi-forever grateful.
 
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