1972 Charger Electrical Issue

[Swamp Ape]

Hello knowledge base,

I have searched here briefly and it gave me some ideas, but I thought I would throw a post up here and then I will go hook up the trailer to retrieve my car.

This car is fairly new to me. I have owned it two weeks. It has been running and driving. I took it to the post office today, and on the way home I lost all electrical power and she shut down. So, I checked the normal issues (Ground, fuses, battery). There was no power whatsoever. Battery was sitting at 13.1V. I found there was no continuity in the fusible link between the starter relay and the firewall. So, I removed the fusible link and added a piece of 14ga wire that I had in my toolbox. I know this isn't the right way to replace the fusible link, but on the side of the road, you do what you have to do.

So with my underrated wire in place of the fusible link, I turn the key on and there is power to the car. The car also turns over, but doesn't start, Like there is no spark. So, I think that maybe I have ruined the ballast resistor. I turn the key on in the car and then use my multimeter to see if there is 12v on the ballast resistor. Before I can really test that, I see that there is now white smoke coming from under the dash somewhere near the middle. I'm no electrician, but I know that electronics have a magic white smoke in them, and if you let that out, they will no longer work

So, I go to Napa. I get a replacement ballast resistor and 6ga wire that will accept a 50A fuse. It is still not a fusible link, but I felt like it should work to get me home. I went back to the car and installed the ballast resistor and the fuse. I turned the key and the car is still completely dead. No clicking, no headlights and she is just dead.

I know there is an Ammeter under the dash that can have issues. That may be my issue. I am not familiar enough with it to know if it will shut the whole car down if it blows. I am going to hook up a trailer and go retrieve the car with a buddy now. Once I get it home in my garage with tools and lights, I will poke around under the dash to see where the white smoke came from. I know there is a rats nest of wiring under there after 50 years of people playing with this car. Maybe I will just have to rewire the whole thing, been there before.

If anyone has any advice, let me know. Thanks in advance for any advice.

 

[LowBikeMike]

You really need to find out where the burnt wire are under the dash, sounds like you have a short somewhere. I'd start by removing the connectors at the bulkhead and looking at them. If you used a regular 14 gauge wire to replace the fusible link you likely melted the wires in a different place because there was not link to burn out first. 6 gauge wire and 50 amp fuse? Holy smokes, where did you put that thing???

 

[Swamp Ape]

You really need to find out where the burnt wire are under the dash, sounds like you have a short somewhere. I'd start by removing the connectors at the bulkhead and looking at them. If you used a regular 14 gauge wire to replace the fusible link you likely melted the wires in a different place because there was not link to burn out first. 6 gauge wire and 50 amp fuse? Holy smokes, where did you put that thing???

I tried it where the fusible link was. It solved no issues . On the side of the road, I figured I’d use whatever I had in my box.
Anyway, I got her home now and in the garage. Ill start poking around under the dash tomorrow to see where I am at. I assume I will find a shirt somewhere in there. In the meantime, I’ll shop around for the correct fusible link replacement.

 

[bandit67]

When I pulled the dash assemble on my 73 I had overheating/melting issues at the bulkhead electrical connector , at the steering column connector as they bypassed the original amp meter. As you are learning now the main power load wire from your alternator to the amp meter and then back out to the battery has been and can be a major problem causer on our 50 year old fun machines. Some known things to cause problems can be loose connections, accessory power loads tapped in at the wrong placement, and plain butchering of the wiring harness.

Nacho has posted an incredible amount of information here helping with repairs and upgradings to the original charging systems. I am sure finding them will help you much in correcting your troubles. If you have some help, pulling the dash is no where as much trouble as I thought it was. Sure makes it easier in inspecting, repairing and replacing wiring and gauges. Thankfully their are replacement wiring harnesses for most all our needs if yours is beyond repairing.

 

[Swamp Ape]

When I pulled the dash assemble on my 73 I had overheating/melting issues at the bulkhead electrical connector , at the steering column connector as they bypassed the original amp meter. As you are learning now the main power load wire from your alternator to the amp meter and then back out to the battery has been and can be a major problem causer on our 50 year old fun machines. Some known things to cause problems can be loose connections, accessory power loads tapped in at the wrong placement, and plain butchering of the wiring harness.

Nacho has posted an incredible amount of information here helping with repairs and upgradings to the original charging systems. I am sure finding them will help you much in correcting your troubles. If you have some help, pulling the dash is no where as much trouble as I thought it was. Sure makes it easier in inspecting, repairing and replacing wiring and gauges. Thankfully their are replacement wiring harnesses for most all our needs if yours is beyond repairing.

Thanks. I started reading a bunch of threads last night. Now that it is in my garage, and not in the side of the road in the Georgia heat, I can start to pick it apart.

 

[Swamp Ape]

Here is a question that has been in my mind.

50 years ago using a fusible link probably made sense. Having a sacrificial length of wire that would fail and save the other electronics. Nowadays with better technology, wouldn’t a slow blow fuse make just as much sense, or more? Seems like a slow blow fuse would be easier to find, built to tighter specs (maybe). I’m not sure if that makes sense. Just something floating through my mind.

 

[Nacho-RT74]

Ok several quick notes I can post with the little information we have:

If you didn't have power inside the cab initially and when you replaced the fuse link with a regular wire the power came back, obviously you had a fuse link issue there. NOW, it means you had a short what made the fuse link fail? No. When the fuse link blows, its NOTICEABLE. IT ACTUALLY BURNS. In fact an accidental small short on an unprotected circuit out of the fuse box that you save before a total fail which will be able to melt the cover bubbling all around like boiling and still could get continuity before the total failure. If you had to test the fuse link to check for its conditions without any visual damage, it could mean the fuse link strands could be cut at the terminal, like any regular broken wire.

Now... are you sure the fuse link is damaged? Did you actually tested for continuity out of the car? Couldn't be a bad contact between fuse link-red wire terminals or the red wire coming into the bulkhead which when handling it got back the contacts making to you think it was the fuse link when replaced for a regular wire?

Is a matter of prefference the fuse link or a maxifuse or anything similar. Myself I'm pro fuse link because is able to hold some power peaks ( like an accidental short while handling wiring ) before melt, while a fuse will blown as soon gets the rate its designed. And you can keep a spare fuse link into the glovebox. Also replaced with a regular wire like you did in case of emergency, once of course you located the fail and fixed it even temporally to get ride you up back to home.

About ammeter.. there is A LOT of info around on board, some of them on the last couple of years which became on hard discussions LOL. Many pro and cons threads and replies around. Making a search you will find I'm a pro ammeter user. BUT THIS DOESN'T mean I'm not concious about the risks of it. How can you keep out of risk? CHECKING, MANTENIENCE, AND PROPPER UPGRADES where they are required. Ppl is afraid about the risk of having a full load ammeter... but HEY! You are driving a tank full of fuel!! Isn't that risky too? One word... MANTENIENCE. electrical parts use to be the most ommited area of the car for mantenience and underestimated. Wires, and specially TERMINALS are under 50 years old of use, abuse and jacks all around from ppl who thinks they know what the hell they are making, just like the rest of the car.

Tipical weak points to check:

ign switch plug down the column. Specially red and blue wires, quite often also the black one.

Bulkhead conections, specially black from alt on engine harness, blue to ballast ( and rest of engine circuit ), and the red one coming from batt ( the one where the fuse link conects ) on forward lighting harness.

The red and black wires, both 12 gauges use to overheat once inside the cab and they are able to take with them the wire covers around. This failure begins into the terminal conections of these two wires

Ammeter... the ammeter is a gauge hard to beat but also it gets A LOT of stress if the car has been abused. They get inner and outer isolation sheets to keep it isolated from cluster housing. Ammeter only handles positive and is a magnetic gauge which moves with the load/current going or coming from/to batt, so doesn't need a negative signal. Needs a total isolation from chassis.

The abuse of the electrical system on the ammeter is able not just damage the isolation but also to damage the internal shunt due the heat caused by the current going through. This heat stretchs the brass shunt and makes the studs gets loosen from it, creating MORE troubles to the current pass, and creating EVEN MORE heat.

One thing we need to say, MaMopar made a mistake installing underrated alternators, not able to source enough juice at low speeds ( iddle ). This made to the system keep sucking power from the batt having a constant Discharge and Charge loop. Having a good alt this stage is saved and makes the ammeter to be in peace most of the time. If you live in the ocuntry where traffic is not a huge issue the Discharge/Charge loop or constant process is not as big like if you live on a city with heavy traffic.

If the factory alt was damaged on the car life and it was replaced with the incorrect alt, this could become even worst!

I can say even more about this, but lets go step by step.

 

[Swamp Ape]

Thanks Nacho. I’ve read a bunch of your electrical posts, and I’m glad you chimed in here.

The car has aftermarket Autometer gauges for Tach, water, oil pressure and voltage. Right before total shutdown I noticed those stopped working. I’m going to see where the PO tied those in to start with. With that being said, nothing else on the dash was working before. It was on my list of stuff to deal with. I guess it is higher on my list now.

I’m going to have to find the time and courage to pull the dash. I have been researching it because I knew I was going to get there eventually, guess it moved up on my list

 

[Swamp Ape]

I’ve spent a little time digging around this morning before family activities take over my time. I found that the wire for the lightbulb on the tach was wired to the ballast resistor, so I removed that. I believe the lightbulb positive wires for all 4 gauges were wired into that. I removed it and installed a new ballast resistor. The old one tested fine, but I had the new one.

I found a connector under the driver’s side dash that leads up the steering column (attached pic). Obviously she took a little heat. I am going to assume I fried that when I used my DIY fusible link on the side of the road. I’m not sure what the wires do yet, but I will figure that out and repair it.

After poking around under the dash, I think I will remove the dash and square stuff away. It is a mess of wires, and I think there are mouse droppings up in there from when Nixon was President.

That’s what I have for now. Thanks for the help this far. If anyone has a source for a replacement fusible link, throw it up. If not, I’m sure it’s in a thread here somewhere.

Thanks again

 

[Nacho-RT74]

Dash is really EASY to be pulled out. It can be made in a couple of hours by somebody who never have made it. I think I can make it in half an hour, maybe 40 minutes. There is a friend who made a video pulling it out following my instructions and if required I can post the link later. I have also a written guide for it.

Is it rallye or standard cluster?

 

[Nacho-RT74]

That's the ignition switch plug.

Fuse links are available at the HELP section, on blisters, on any parts shop around...or I think it uses to be there. I'm not "American" neither live there. I have been in the states just for one month back in 2008 for Carlisle All Chrysler meeting. My Charger was assembled in Venezuela where I was born... living at this moment in Spain.

Those replacement fuse links use to require to attach the propper terminals per your need. Some of them have at least the eyelet terminal for the starter relay stud.

The terminal to the red wire going to bulkhead it calls Standard Molex. Its also available around sometimes in bulks.

 

[451Mopar]

Make sure the alternator is not shorted to ground (bad output diodes or insulator.)

 

[Swamp Ape]

Dash is really EASY to be pulled out. It can be made in a couple of hours by somebody who never have made it. I think I can make it in half an hour, maybe 40 minutes. There is a friend who made a video pulling it out following my instructions and if required I can post the link later. I have also a written guide for it.

Is it rallye or standard cluster?

Thanks, I’ll check out the fusible link on the home page. I think the dude who did the video from your instructions was Vic’s Garage. I think I watched that a few days ago and he gave a shout out to you. I subscribe to his channel. It looks easy enough, much easier than BMWs and other newer vehicles I’ve worked on.

Thanks again.

 

[Swamp Ape]

Quick fusible link question:

How do I know what gauge is appropriate? Just match it up to the fried one? I have read 14ga, but I am not sure. And the people at the local parts shop on the weekends are not always the most knowledgeable.

 

[72RoadrunnerGTX]

The red & black wires at the ignition switch Molex are a common weak spot, better off replacing with better connections that can handle normal loads there. High resistance there would account for a no-start/run condition but not a completely dead electrical system, the charging circuit Packard connectors at the bulkhead are more likely to be causing that. Again, under rated current handling, have been a problem since early on. By-pass the bulkhead on these two circuits.
Also, carefully inspect the ammeter connections, make sure there is no heat or insulator damage caused by previous misuse.



BTW, the dash removal described here is nothing new, it is simply the reverse process of how the dash was installed on the assembly line, the removal procedure is clearly detailed in the factory service manuals from the day. It’s just few more minutes to pull the steering column out completely, makes the dash removal way easier, zero chance of damaging anything.

Stock loads, 14 ga, is fine, wouldn’t be too concerned with any disconnects on the fusible link, a quality splice and a good, crimped ring terminal will be more reliable.

Anderson Powerpoles

 

[Nacho-RT74]

the stock fuse link used is 16 gauge.

tipically the fuselink to be used should be 2 sizes smaller than the wire where is connected.

if you think on an alt and wiring upgrade, yes, 14 gauge is good enough. Is what MaMopar made too for fleet cars and heavy load setups. In MY opinion, never larger than that. You must keep a weak spot there were any trouble will find its place to burn.

yes, Vic is the guy who made the video.

Anderson Powerpoles conectors mentioned are a GREAT solution and upgrade for the ign switch path if you are already in troibles there. On my car I had that problem, but since I fixed the stock Molex conectors, I haven't had any other problem. Sure I keep an eye on them. I'm also a "stockish" guy, so where is posible I try to keep the stock stuff.

Anderson Powerpoles conectors could be also a nice idea for the fuse link conection to the red wire runing to the cab.

 

[Swamp Ape]

Thanks y’all,

I’ll tear into it as time permits. Doesn’t look like an overwhelming issue, just need to find the time.

 

[Nacho-RT74]

Pretty sure you'll find the fuse links at your local parts shops

they can be like this

or

or with the eyelet terminal attached, so just will need to work on the other end

also NOS/new repro if you want to pay 30x times the price LOL, but will be a plug and play and just in 16 gauge ( just like factory )

But I bet don't even need to run into the guys at the counter, just go to the exhibitor and will find the blisters there

or even get a roll and make a stock of them ready to fit ( which is what I have made for some buddies' cars )

 

[Swamp Ape]

I found the Dorman brand at Oreilly. Bought a few of them

 

[Swamp Ape]

Alright folks, I got the dash out. I didn’t want to, go this deep right now, but here I am. I started with just pulling the cluster. As you may recall, the cluster has not worked since I bought the car. Well, I found out why. The main power wire to the cluster was shorted out and melted. I followed that back to where it disappeared. At that point, I figured I may as well pull the dash.

between the extra wires wrapped around misc other cables, and stuff zip tied together, it was a bear. But, it is out. I diagrammed wires and labeled them. Hopefully that will help when it comes time to put it back together.

the big question I have now is, should I cut out the bad wire and solder in good wire, or should I buy new wire harnesses? I have made my own harnesses for motorcycles, so I am not overly concerned there. I assume I can buy harnesses online somewhere, I just want to make sure I get the right ones. If someone has a source, post it up. If not, I’ll do some searching later today. Headed out to do the family stuff.

what else should I do while the dash is off?

Thanks again.