Burned bulk head connection

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Machmeter1

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I went through the engine wiring harness and found out, that the connection for the black cable, comming from that Alternator, is badly burned. All other connections look quite good.
After reading some posts here, I learned that this is a common Mopar problem. For now I don't want to dissemble the whole dashboard, but I am checking the all accessible connections and cables. I am planning to uninstall the dash next winter.
Anyway, this connection has to be addressed immediately.

So that's the plan for now:
Remove the faulty connector and widen the hole with a drill. Run a new wire from the alternator through this hole and connect it on the inside of the fire wall to the other black cable. I would like to use some quality plug for the connection. The engine harness would still look original.

I found an interesting article about running a parallel wiring from alternator and starter relais to the ammeter. I am planning to do the same but not sure if that would make much sense, and what kind of wire and fuseable link (sizes) to use.
I have to confess, that wiring is not one of my strong points.
Appreciate any opinions and advices on my plan. Here are some pictures, showing the burned connection and the wiring diagram I am planning to follow.
Thanks Wolfgang

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poop

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View attachment 1715472696
 
The black wire from the ammeter is joined to several other wires (headlight and fuse block and maybe one more component) in the cabin that might require attention since you have a burnt w I re from the alternator. Just saying!
 
First thing to do is read the MAD article. Even if you don't perform that mod, that article has a good simplified diagram of the current path and explains the "why" of the problem

Catalog

If you don't have a service manual go to MyMopar

MyMopar - Mopar Forums & Information - MyMopar Tools/Reference

Wander around in there, there is lots of great info, as well as free factory service manuals (which contain factory electrical diagrams) as well as aftermarket diagrams under "wiring" which are sometimes easier to follow but may not be completely detailed

You can buy the connector terminals for those connector shells they are known generally as "Packard 56". You must be careful to get the correct ones.
 
Hi thanks, I do have service manual and read the Mad article. I also know that the black wire has several connections inside the firewall. Everything looks good there it's just the connection at the bulkhead.
I am planning to run the parallel wiring shown above and mentioned here.
Some considerations about the charging and wiring upgrade and your worries about
Would that make sense and if so, what size of wires?

Thanks Wolfgang
 
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Crackedback came up with a simple plan on this. You make sure what is "originally" there is in good shape and then run a fused/ breaker protected wire direct from the alternator to the battery. This turns the two wires that go through the bulkhead into a feed into the interior, and relieve that end of things of the charging current.

If you want to keep your ammeter, that gets more complicated. You really need to upgrade the wiring size. The ORIGINAL cars which came with heavy duty 65A alternator HAD a sort of factory bypass. They ran the ammeter wiring through separate gromments in the firewall. You can look this up in some of the service manuals over the years.
 
I’m not sure why 65 (and 63) harnesses both had the wires from the battery and ammeter connected to heavy duty buss bars at the junction box. Then inside followed the customary branching off with the black wire. It could certainly cause problems at the spice but not at the junction box. On my 65 I am running through maxi fuses a modified harness the 2 wires to the ignition switch and one direct to the headlight switch as Mopar did in the 80’s
 
Some do not agree with the mad article and if possible I would like to keep my ammeter. That's why I posted the wiring diagram with the parallel system.
With Ammeter or without, most important now, I want the wiring repaired and safe.

Thanks, Wolfgang
 
Some do not agree with the mad article and if possible I would like to keep my ammeter. That's why I posted the wiring diagram with the parallel system.
With Ammeter or without, most important now, I want the wiring repaired and safe.

Thanks, Wolfgang
It always helps to know what year, model and options are on the car.
From your photo its obviously not a 63 or 65 which had a better connection than most other years.

The usual bulkhead connector terminals are small for the current they have to carry. But the terminal at the alternator output stud is usually pretty big. If that one is also burnt, lets see it. Certainly glad to help you do a parallel bypass (like Nacho suggests) but also would like be sure there is not some excessive load that has caused this overheating.

Since the bulkhead connector is damaged, but not badly, I'd leave that as is and run the new line through a grommet like the some a-bodies rear defroster grids got.

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Looks like a '69 from what I can see of the diagram. Yes?

'69 shows only 12 gage wires used on the main feeds, except battery to starter relay.
You've got a few choices on the alternator feed. Not seeing any advantage to drilling through the bulkhead unless you want to keep the routing looking very stock. Some sort of heavy connector with lots of surface contact area. Maybe a molex or similar bullet connector.
Other choice is route new wire through a grommet with a ring terminal to go over the ammeter stud. That's what Nacho did. And he left the original wire in place. In your case you'ld have to make new one and ther terminals may not hold well in the damaged connector.

Or run one or two wires through a grommet. One to the ammeter, the other connect to the original alternator feed inside.
If two wires, I'd make them both 12 gage. If just one, might as well go up to 10 gage.

Posted recently by a member parting out a defroster grid equiped '73
These are the connectors Chrysler used.
One wire direct from the alternator output, the other from the battery.
View attachment 1715472758
Ring terminals went to the ammeter.
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Mattex thanks, sorry forgot to mention it's a 69 Barracuda. Will go to the garage later and post more pictures of the electric components used.
 
Way WAY back in the early 70's my 70 RR bulkhead connector failed. I just drilled it out and fed some large were through there. The ammeter, tho, itself can give trouble, and in rare cases, the welded splice can fail. I found "my" first failed welded splice in that same time period, on a friend's 68RR. I used to insist on ammeters, myself, but I finally converted mine to a voltmeter There is an old thread, somewhere, on doing so Here

Ammeter to Voltmeter...who does it?
 
Ok. Thanks for the pictueres.

Now that I 've had dinner and reread what you wrote, I misunderstood - I thought there was more obviouse damage.

Good looking setup. Is that Year One /M&H harness ?
Maybe more important, what alternator? and is there anything else besided the electronic ignition added to the car?

I guess its not clear what your priority is for the car. If you don't want to have a wire through a grommet, then yes go through the bulkhead. I don't understand the connector question in that case. Just hard wire it because it will have to be cut no matter what if if ever does need servicing in the future.

I'll rework a diagram that's based my '67 Barracuda into a '69 and walk through what apparently happened.
 
Hi, the ballast resistor is modified to let 12V going through (got it from halifaxhops), other than that everything should be stock. Removed all the performance stuff, which the privous owner added. I wanna keep it stock, besides the electronic ignition. Alternator should be 69, will post a picture tomorrow. Just checked the wires inside the firewall again. So far they seem to be in great shape. If I just replace the black alternator wire, would it make sense to add a fuse or other safety feature in it, just in case the wire gets too hot?
 
the ballast resistor is modified to let 12V going through (got it from halifaxhops)
well then it prob has an HEI module in the ECU. Those modules control current internally. Best thing with that is ask @halifaxhops.
Don't think that's related at this point.

If I just replace the black alternator wire, would it make sense to add a fuse or other safety feature in it, just in case the wire gets too hot?
Not on that wire. The question is why did it get too hot.

Here's the wiring diagram reduced to the power and run circuits.
The location you're seeing showing overheating is P, and so far no where else.
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All I can suggest from that evidence is a bad connection at P.
If the battery was either drawing or providing a lot of power, we'd expect to see similar damage at J.
Also you probably (hopefully) would have noticed the ammeter spending a lot of time away from the middle (zero) position.

Maybe it would help to discuss what the drawing above shows.
If the engine is off, key is off, all of the wires connected to the battery's positive post are at battery voltage. Lets call it 12.8 Volts. No current is flowing.

If the dome light or parking are turned on, current will flow through the battery feed, through the fusible link and the connector, through the ammeter to the fusebox and eventual through the lights and back to battery negative.
The current flowing through the ammeter will cause the needle to deflect showing discharge.

With the engine running the alternator can produce power at a higher voltage than the battery. So instead of the battery being the power source, the alternator is the power source. In fact, if the battery is low (such as after starting) is will draw current. When current is flowing to the battery, the ammeter needle will deflect toward charge.
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It doesn't take much power to run the ignition and alternator field. Showing 4 amps in this example.
Battery charging will draw less and less current the closer it gets to fuller to fully charged. Showing 8 amps in the illustration. The gage is roughly 40 amps to 40 amps. If you see over 20 amps for any length of time - there is a problem and need to figure out why.

Even without the battery charging, if you're driving at night or in the cold and rain, the current drawn by the lights, wipers and heater blower adds up.
Light are about 9 amps plus parking and instrument panel, lets say 5 amps to the wipers and 5 to the heater fan on low and now its up to 27 amps.

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The connection at P is the weakest junction in the alternator output line. It's possible it was just not making a good connection or either terminal didn't have a good crimp. The heat is generated by current and resistance. More of either and the more heat will be generated.
Its also possible something is drawing more current than normal. This could be because voltage is regulated too high, but then we'ld expect to see other signs. To be safe, it wouldn't it hurt to check running voltage at idle and fast idle or 1250 rpm.

Running a parallel wire through a grommet to the ammeter does two things.
1. If the battery needs charging, that will be the shortest path. Current for recharging will not go through the bulkhead connector but directly to the ammeter and then to the regular charge path.
2. If there is excess resistance through the bulkhead connector, electricity will take the parallel wire with less resistance.
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From the picture on post #8. I took apart a 70's dodge pickup with the big alternator years ago. It had this same harness with the big wires [#8, I think]. There was a brass strip behind the ammeter. It acted as a shunt. This took some of the amperage away from the ammeter. Never saw any signs of heat damage.

If you have a good working system now and want to add a bigger alternator, just ADD a wire of the same size as the alternator wire [# 12?] between the alternator post and the positive battery terminal. [with a fusible link]. Your ammeter will read half current, or so.
 
Hi, the ballast resistor is modified to let 12V going through (got it from halifaxhops), other than that everything should be stock. Removed all the performance stuff, which the privous owner added. I wanna keep it stock, besides the electronic ignition. Alternator should be 69, will post a picture tomorrow. Just checked the wires inside the firewall again. So far they seem to be in great shape. If I just replace the black alternator wire, would it make sense to add a fuse or other safety feature in it, just in case the wire gets too hot?
Thought that was for petronix?
 
From the picture on post #8. I took apart a 70's dodge pickup with the big alternator years ago. It had this same harness with the big wires [#8, I think]. There was a brass strip behind the ammeter. It acted as a shunt. This took some of the amperage away from the ammeter. Never saw any signs of heat damage.
Interesting that it was external. You're thinking it was a second shunt (in addition to the internal one). Could be. And the needle movement could have been calibrated to account for that. Or maybe they just changed the owners manual. LOL. If it said anything - instead of 40 to 40, optioned trucks get a 80 to 80 ammeter. :)
 
Its also possible something is drawing more current than normal. This could be because voltage is regulated too high, but then we'ld expect to see other signs.

This might be information overload, but the damaged connection at P would be a cause high voltage alternator output.
As current flows through resistance, voltage drops.
If the connection causes 0.1 Ohms resistance and there is 4 amps flowing through it, that's 0.4 Volts lost.
That would be tolerable.
But if the current is higher, or the connection gets worse, it can be a problem for correct regulation.
When voltage is lost on the way to the regulator, the regulator drives the alternator to bring the regulator input into the target range.

Lets say connection a cavity P had 0.1 Ohms resistance and every other connection and wire has no resistance (ideal).
Using the example of an engine running and battery recharging at a moderately high rate:
12 amps x 0.1 Ohms = 1.2 Volts
If we measured voltage to ground at various locations, we'd see the regulator input still at 14 Volts, but the alternator output at 15.2 Volts.
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Power is volts times current.
1.2 Volts x 12 amps = 14.4 Watts. That is 14.4 Watts of heat.
 
Hi, still have the original resistor and will put it back. Here's the final part, the Alternator. Looks like a 65 Alternator, but it is in good shape and worked.

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The ignition module in my car is not listed in the wiring diagram of my 69 service manual. The black and yellow wire from there should go to the - on ignition coil, the two grey wires go to the distributor I got from Halifaxhops.
 
Hi Hops, does the distributor you send me match the ignition module in my car and should I keep the original ballast resistor in it's place?
 
Hi, still have the original resistor and will put it back. Here's the final part, the Alternator. Looks like a 65 Alternator, but it is in good shape and worked.

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First photo shows the casting date. 1965 is the year. The little dots reveal the month and day.
If it was never rebuilt the part number can be cross referenced to the rated output.
The part number is a stamping on the side where the output stud is located.
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This one was p/n 2642537 and originally assembled in 1969.

If its been rebuilt, then its hard to know if they kept the rotor and stator together with the case. Depends who did it.
Really doesn't matter much for typical everyday use. More of an issue if doing a lot of idling, especially at night or in bad weather or with A/C on.
 
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