Underdash Harness bunt up

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Ivoryk3ys78

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In my 72 Plymouth Duster the underdash harness burnt up pretty good. The ammeter wire basically got several other wires hot and melted several wires. It also melted some wires into the bulkhead connector.

A new harness at Classic Industries is like $700. I can not do that. I am wondering what other years are compatible and if both A and B body are compatible. The care does not have AC.

Also he suggested looking the ammeter in between the battery and the alternator with heavier guage wire and just running that through a grommet in the firewall instead of having it pass everything through the ammeter wire. That seems like a good idea to me. Is there anything to be concerned about there or any tips on that or any of this.

Thanks a lot
 
whatever fix for the burnt wiring you choose, the biggest challenge is figuring out what made it all burn up in the first place or it will just burn up again. Do you have non-stock electric equipment in the car - big stereo, high load headlights, etc? What is the amp rating on your alternator? Lots of new ones are over 100 amps. The stock wiring was made for stock loads. You can get around all this for those features, you just need to plan for them.
 
We kinda just got this car running a couple summers ago and it's been driven very little. I think the alternator on it just a 60 amp. The radio is not hooked up, the heater core is not being used. It is very basic. My friend said it looks like the ammeter wire had heated up over a long time most likely.
 
Lots of research to do before swapping out your harness. I'm not saying the swap isnt needed BUT it's not just a plug and play and be done with it. Make sure to get factory schematics. And factory schematics for your donor harness.
Google "Mad Bypass"
That will help id some of the problems with factory mopar wiring.
Not an easy job, only wanna do it once and get comfortable lol. Remove seats to make it easier.
Good luck.
 
Also we can just bypass the ammeter entirely and jsut use the volt meter in my triple gauge cluster.

Need to find a wiring harness though. Mine has 6 or so burnt wires.
 
There's a soldered positive "tree" that's taped up right from the factory. Like six or seven positive wires all soldered together. Like something out of a real hack shop, but right from ma Mopar. I've seen a lot of those have the tape just rot off and sometimes they "find" ground with really nasty results.
 
I suggest a full replacement. If you love this car then do it right! Save up the cash! Also there are very good points previously posted! Why did it happen? Most just sell the main harness, there are several additional supplementary harness assembly’s in most cases!
 
Stupid question but when we had things part the piece that goes from the wiper motor to the wipers themselves was not even in there. What is that called so I can order one and get it before we get things back together.

Also the fuel gauge does not work. It is not the sending unit. Can a person put a new gauge in there?
 
Also the fuel gauge does not work. It is not the sending unit

It might not be the gauge. Could be the voltage limiter, 'specially if the temp gauge has issues as well. Don't just throw parts at it.

The ammeter wire basically got several other wires hot and melted several wires. It also melted some wires into the bulkhead connector.

The fusible link should have failed first. It is between the starter relay to the bulkhead. Often they kill the plastic at the bulkhead connector when they fail. Evans wiring sells just the plastic if you want to keep it original and fix the harness without a whole new one.
Likely the wires came loose at the ammeter or the bulkhead connector. #1 issue with our Mopars. If you're good at fabricating and have access to a wide selection of wire, Packard connectors, pro-quality crimpers, you could make your own harness. Or go aftermarket like American Autowire or Painless. Evans have most everything except the dash harness. I'd recommend a new engine harness. I replaced mine on my Charger (along with a new Packard connector at the inside bulkhead for the fusible link feed) and it cured my charging issues.

EvansWiring.com : Product Catalog

Sign up for Year One's emails. They'll have a 20% off sale, your down to 580.- Looks like there is an early and late 72 harness. Maybe someone else on here will know the difference.
 
Also we can just bypass the ammeter entirely and jsut use the volt meter in my triple gauge cluster.

Need to find a wiring harness though. Mine has 6 or so burnt wires.
No. I mean you could but the problem wasn't in the meter unless it shows damage. In spite of all the Chicken Littles on the internet (such as MAD), the evidence you are looking at tells the story. The wire got hot. The wire got hot for one reason: resistance to current flow.
Any place you see evidence of heat damage is a location where there was resistance to flow.

The next question to answer is why was there resistance at those locations. Since it looks like a gradual deterioration, some of the most likely possibilities are:
Someone charged a dead battery while driving.
Connections were loose and oxidized (this includes broken or corroded wire strands at the crimps)
Wire itself was corroded (less common but it happens - cut open the insulation and its not bright but green!)
Power supplied at higher than 15 volts. (This can cause battery recharging at too high of a rate and continue to draw current even when its fully charged.)


Stupid question but when we had things part the piece that goes from the wiper motor to the wipers themselves was not even in there. What is that called so I can order one and get it before we get things back together.

Also the fuel gauge does not work. It is not the sending unit. Can a person put a new gauge in there?

Send the gage out for repair. The reproduction gages are never correct.
First check the wire connection and ground clip connecting the tank to the fuel line.

Wiper linkage parts is what you'll need.

A parts book and a shop manual will help with these things. You can buy used or reprints or CD versions from places Bishko and also in the for sale section here.
There is a scanned 72 Plymouth manual here (free to download)
MyMopar - Mopar Forums & Information - Service Manuals

and Parts books here (also free)
MyMopar - Mopar Forums & Information - Parts & Accessories Books

Barry and his buddies have collected and scanned many of the service bulletins that updated and correct those manuals.
For those, look here under 1972 TSB
www.imperialclub.com/Repair/Lit/Master/https://www.hamtramck-historical.com/library.shtml
 
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Most 1972 A-bodies have just one power distribution point in the wiring system.
It's a welded wire splice joining the power feeds (alternator and battery) to the various circuits.
It's usually fine. But if there is a problem there, that's trouble. All power flows through it.
The connectors most often are the weak spots. The bulkhead connector has already been mentioned, and on a '72 it would be worth checking the steering column connector as well.

The fusible link didn't melt, so that's indicates whatever the problem(s) are, its not a short to ground.
http://www.heritech.org/cuda/Charge.html
 
Main power and ignition circuit schematic.
Cars have two power sources:
Battery
Alternator
Power flows from whichever one can supply at the higher voltage. Battery is 12.5 V, Alternator around 14 Volts when running.
The output from each is joined at the main splice and distributed from there.
The battery output becomes the battery's charging wire when the battery is low.
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Practically speaking. Look at the wires and connection terminals. Mark which ones are damaged.
If its just a couple wires and does not involve the main splice, they can be replaced.
Main splice can be repaired too - but you want to really do a good job. Your friend may be so skilled - if so - go for it.

Most of the terminals are Packard 58, some Packard 56, and the column connector uses something like a molex.
The main feeds can be run through a grommet instead of, or in addition to, using the bulkhead connectors.
Chrysler did that for some a-bodies optioned with 59, 60 andor 65 altenators, at least some years.
 
Check Year One, I just ordered dash and rear harness for my 66 Cuda. They had a pretty good discount on.

Tim
 
Is the bulkhead connector melted too on the inside or outside? I've seen harnesses like this that were hot over a long period of time. If those connections were corroded could it result in a level of resistance that would cause this damage? Those bulkhead connectors are a weak link in the system - Chrylser never built them with 50 years of use in mind so the corrosion is slow and progressive. Hardly anybody pulls them apart before they have problems and cleans the terminals and repacks with di-electric grease to keep them functioning properly.
 
I had the exact issue you're having on my 72 Charger. Whatever the cause I'll never know. Was it the old corroded wiring, or the poor firewall connections? ( I bought the car all burned up like that) So I have no idea what the previous owner had done.

I also did not want to spend $700 on a whole new harness. I found a guy at Mopar's in the Park last year that was selling used good harnesses. I think I paid $250. I can try and find his card from last year if your interested.
 
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