65amp wiring/trouble shooting

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Here's a '73 that wasn't sandblasted. It may have never been opened or worked on, but no tag, so I think it was opened at least once before I got it.
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There's also a casting date on the front shield.
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4spdragtop said:
Each cars wiring issues are unique. I'm not electrically talented, its voodoo to me lol. I did the MAD amp bypass as I was having elec issues and saw the amp gauge flicker a few times(smelled some smoke too).
The bypass may or may not be a benefit to you, but one thing for sure, clean all bulkhead connections thoroughly, and check for melted burnt wires. Our 67 wiring was in good shape, but the insulation was cracking. Harness was 55 years old...I made a new harness, tedious but I enjoyed it.
Heres what I followed for the bypass.
Catalog
Click to expand...
Is MAD even still in business?
 
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copy.jpg
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I am not understanding why you guys are getting so picky about alternator numbers. There's a pretty good chance, as old as these girls all are, that it has been a rebuilt at some point. It may not be what the numbers claim.

One thing is for sure. That car originally had the optional 65A setup
 
I looked up the regulator to be sure it was not anything special to that package.
Mark then got curious about the alternator.

It still has the original alternator, and if there ever comes a time where it needs service or replacement, it should be serviced not replaced.
 
Bugman said:
half page might show up better

View attachment 1716023461
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Best I can tell from Mark's photos and description is that wire C13 for the back lite heater was spliced into R6E in the engine bay, rather than hung from the ammeter stud on a ring terminal.
Hopefully the fusible link is 16 gage as shown in the diagram.
Those appear to be the differences between what is on the car and the diagram.
 
RustyRatRod said:
I agree with locating and repairing the problem FIRST. That way, you know what's working and possibly what's not. Could be it was just a fluke of a wire rubbing against something through the years and finally got the insulation off and grounded, once repaired, it may never do it again. It all depends on what you want to do with the car. If you're like me and the most you're going to do with the electrical system is a small sound system and electronic ignition, the stock electrical system will be fine, if it's in good shape. Adding electric fans, a lot of tunes and whatnot and you will probably want to make changes like the amp gauge bypass. But unless you repair what's there first, you may end up repeating the problem. That would suck.
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The question now is how to repair this cable. Do I need a completely new cable or is it enough to repair it? And if it is good enough to repair, how? I mean, the insulation melted away a bit. Is it enough to take some insulation tape? Or is it also possible to cut off the melted part and add a new crimp connection? The only part that melted is where it is screwed down on the ammeter, as shown on the very first picture.
 
If it is melted near the ammeter, that IS a huge clue. The ammeter is likely a problem. Here is the way they die

Typical Mopar alternators do NOT have the studs welded/ soldered, or sometimes not even crimped to the "guts" which is the shunt. All that current goes through there. The thing makes connection by the idea that it's all clamped together, except "it's not", sometimes. The insulating washers compress and come loose, some of these girls have plastic components of the cluster sandwiched in there, and the plastic compresses, the thing heats up because it's loose, and the heating causes it to get even more loose

You need to either fix it or bypass it. You can (if you are handy) take the ammeter apart, and silver braze the ammeter studs to the shunt. Then, you tighten the connections jam nut--to stud/ connections--to jam nut, and it will not matter if the junk in between comes loose.

IF the end terminals of the wire(s) in question look burned/ corroded/ cooked, I would cut the wire back and replace the terminal, or whatever else you need to repair it.
 
If the battery was getting 20 amps at 18 volts, that was the result of a problem in the branch feeding the key switch, not the branch going to the battery. Any damage at, in, or near the ammeter would be due to the long period of overcharging.
If the studs to the ammeter are loose - then it must be repaired. Those are a press fit to the metal plate connecting them together.
If the only damage is at the wire ring terminal, then fix that. A little De-oxit on the metal. For the insulation, some liquid electrical tape, and a wrap or two of tape keeping that boot/seal shut where it split. It's going to be very difficult to do a quality job replicating that factory ring terminal connection to the 8 gage wire.

At one point you measured 18 Volts at the battery, and at least 10 amps or more going to the battery.
18 Volts at the battery can not be caused by poor or loose connection in the ammeter.
It got to 18 Volts because of a fault in the charging system (grounded brush or green wire, regulator itself) or in the circuit wiring from the alternator after it branches.
To understand that take your finger and follow the path from the alternator output to the regulator input (blue wire).
We know the alternator was producing power at least 18 Volt. IF the regulator was seeing low voltage then the resistance had to be along the path to the regulator, not the path to the battery.
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Note that we didin't fully figure out the connections.
It could be like this.
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it doesn't really matter if there system Voltage now measures the same when you test under loads.

If it doesn't, then trace back along the current path until you find a junction where its the same as the alternator output voltage.
The fault(s) is then downstream.
 
SlantedMark4 said:
Since my amp gauge wires melted a bit I'm thinking about an amp gauge bypass. I still have two wires in good shape from another dash to replace the burnt ones but imo this doesnt solve the problem.
The thing is that I have no idea about electrical stuff at all and I don't wanna burn down my car because of bad wiring and I have not really found out where to start working on the bypass. Can you guys help me? I've also thought about to bring the car to a local classic car mechanic to do the job....
The car has a new Voltage Regulator and new battery btw and if the VIN is correct, there's a 65A Heavy Duty Alternator Option listed if not changed over the years.

View attachment 1716021295

View attachment 1716021296
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Why are you using old wires from somewhere else, just get new 10 or 8 gauge wire. Keep the amp
 
Dave999 said:
if the car is standard and doesn't have
1) electric fuel pump
2) electric fans on the radiator
3) super bass 300watt amp and a sub woofer
4) halogen headlamps
5) kettle for making a cup of tea
6) electric fire for those cold winter days

you get the picture basically stuff that would use way more current than standard

AND you didn't replace the orginal alternator with a 150amp sucker off a modern fuel injected vehicle
and you battery isn't way over spec and constantly half flat.

The wires got hot probably due to resistance of that connector where it goes onto the gauge

in which case
repair wire or its insulation first

clean the connectors, and make sure they go on nice and tight. if they bolt on with a nut use 2 spikey washers and smother the connection with grease

Then i'd go a check my headlamnp switch
and my igntion switch for similar hotness

the issue is really....
They never expected your car to last more than 5 years..
The connectors are exposed to the atmosphere
The connectors are made of a brass type alloy that includes a high % of copper potentially some tin and other metals to make a springly gold coloured alloy for the connectors
these metals when exposed to oxygen and humidity in the air corrode and gets a type of tarnish or rust on them called verdigris
white/green/black dusty tarnish

it doesn't conduct electricity unless its a bit damp meaning the contact patch between male and female parts of the connectors gets smaller and smaller as the greeness spreads into the junction, and a tiny contact patch carrying a high current gets mighty hot
its like you reduced the thickness of the cable at that 1 point down to a size that is trying to burn out under the load.

by cleaning up

1) ammter connector
2) ingnition switch connector
3) bulkhead connector
4) battery clamps
5) both ends of earth strap between body and engine and battery negative and body

you can make an improvment to performance of the car that you feel in the seat of your pants

small brass wire brush
small set of pliers for bending connectors to get better clamping
bag of assorted spikey washers
and a tub of vasaline

will make for a boring but successful weekend of car fixing..
Click to expand...
Don't need connection grease
 
Here are the results after manually examining 74 thru 76 wiring harnesses with heated rear glass which had the 60 or 65 amp option. The 74 service manual does not show the 2nd brown wire that is spliced into the #1 main brown wire from the alternator.
Going over this one more time, you have two brown wires and one red wire entering the grommet from the engine side of the firewall. So one brown wire and one red wire go to the ammeter.
Now for the mystery of where the second brown wire goes after it enters the grommet. The second brown wire splices back into the number one brown wire right after it passes thru the grommet. What you have is a short brown wire that is spliced into the main #1 brown wire on both sides of the grommet. Why would Chrysler design it like this?
In 75 and 76 there is no second brown wire. The brown wire from the alternator goes straight thru the grommet to the ammeter. The red wire from the starter relay also goes thru the grommet to the ammeter. Why the strange splice in 1974?
 
Bugman said:
might help

View attachment 1716025083

View attachment 1716025084
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The missing or contradictory information is the other end of wire C13 12 BK (power feed for relay).
According to the main diagram it should be shown in the drawing for CI 5 (ammeter terminals).

On Mark's car, which is equiped with the 65 amp option, which is probably wired the same as 60 amp, we know the grommet carried a second black wire around 12 ga., which joins a second brown wire that is likely welded to the alternator output.

I think the only definative answer will be on the cars themselves, or if available, assembly drawings and service bulletins for 1974.
 
To wit
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Based on what we see on the example in this thread, it appears the factory left as much of the standard harness in place as they could.
For example A1B 10R and fusible link A1C 16 DBL could have easily been removed, but it wasn't.

Therefore if I had to guess, following that logic they would have left R6C attached to the ammeter stud. The heated back light feed therefore would be the one spliced into the alternator output line R6E
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Easier to follow when laid out like this.
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Best to verify on the car!

IMO it is worth the small effort to verify for two reasons.
1. If the voltage issue has not been resolved, knowing the current path will make it possible to track down the location(s) of the resistance.
2. If questions arise in the future, either on this car, or other similarly equipped '74 models, it will save a bunch of time.

3. If someone is looking for replacement parts, they will know what to look for. Specifically how the '74 version may differ from the '73 etc.
 
Mattax said:
To wit
View attachment 1716025123

Based on what we see on the example in this thread, it appears the factory left as much of the standard harness in place as they could.
For example A1B 10R and fusible link A1C 16 DBL could have easily been removed, but it wasn't.

Therefore if I had to guess, following that logic they would have left R6C attached to the ammeter stud. The heated back light feed therefore would be the one spliced into the alternator output line R6E
View attachment 1716025124

Easier to follow when laid out like this.
View attachment 1716025125

Best to verify on the car!

IMO it is worth the small effort to verify for two reasons.
1. If the voltage issue has not been resolved, knowing the current path will make it possible to track down the location(s) of the resistance.
2. If questions arise in the future, either on this car, or other similarly equipped '74 models, it will save a bunch of time.

3. If someone is looking for replacement parts, they will know what to look for. Specifically how the '74 version may differ from the '73 etc.
Click to expand...
Most of the time, it's people using the wrong fusible link, or not replacing old ones after a while
 
All 74 Valiants used the same instrument panel wiring harness, part number 3764208. The only modification made to the standard harness with heavy duty alternator was the A1D 12R which was capped as seen in the CI 5 diagram. A separate wiring harness was used with the heavy duty option, part number 3764270 which was tapped to the standard harness.

Using the CI 5 diagram as a reference, there is only one red wire connected to the + side of the ammeter. In the same diagram, two wires are shown connected to the - side of the ammeter. Actually three wires are connected to the - side of the ammeter stud.
R6C 12BK goes to the standard welded splice used in all wiring harnesses.
R6D 8BK goes to the alternator used with the heavy duty option.
C13 12BK goes to a 30 amp circuit breaker part number 3764198, which is completely separate from the fuse block. From there it goes to the heated back-lite relay. There are some omissions and mistakes in the factory service manual wiring diagrams.

Also just wondering why everyone is calling it a 65 amp option, when the parts catalog and the service manual wiring diagram refers to it as 60 amp option.
 
See the first photo in post 36, and the link to the dealer book in post 47.

For the actual wire connections on this car see the OP's photos. Clearly there are some differences between what the book shows and what is there. Agree the book's diagrams are not error free.

It will be interesting to learn what @SlantedMark4 finds with respect to the alternator tag and other details.
 
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