73 charger, wires melting/melted

[Lewis]

Hello all, I am new to this so bare with me!! I bought a 73 charger recently and I can't get it to start, when I mean start I mean I am getting the same feed back as though trying to start a car with no battery that's what's happening, no lights horn, ignition nothing at all, a lot of the wires under the dash have melted so I have re wired them all thinking that was the problem, yesterday I went to plug the battery in and straight away the was a puff of smoke which led to my car nearly setting on fire, and the wire that melted was a red one coming off the starter relay which looking at the wiring diagram its labeled as battery just to clarify its not one that I have retired!, what I don't understand is what happened and why It happened!! I really need help as I am out of answers! Sorry for the long post!

[GOTWING]

this is a familiar nightmare I had, I had to purchase a complete used wiring harness  if you take it on you will be like 

[Lewis]

I know I am saving for a new wiring harness but I am from the UK so import it a big deal so just trying to see if it actually works before I throw money at it

[Lewis]

Also just to add I have a 800cca battery with 95ah which I read is the one I need, just didn't know if it was to much and that was the reason the wires are melting

[nascarxx29]

You got a electrical short not caused by a battery application  

 http://www.mymopar.com/downloads/1973/73CoronetChargerA.JPG

http://www.mymopar.com/downloads/1973/73CoronetChargerB.JPG

[Lewis]

Okay thank you, any idea where that may be? Not great with wiring haha

[nascarxx29]

Check all power leads from underhood wiring to firewall bulkhead to amp gauge to fusebox  for damage and isolated what area and wires are most damaged.then using wiring diagram.go from there with a 12 volt testlight.and a bad alt or voltage regulator could overcharge electrical system.anything from a battery cable from starter making ground and causing a short or any carrying power ground shorting will cause melting plastic.  http://www.dodgecharger.com/forum/index.php/topic,59308.0.html

[Lewis]

Thank you that's very helpful!!!!! I don't have a voltage regulator I can see where it's meant to be but it isn't there don't know why, the air conditioning unit was taken out and most of the wires cut not removed so they are just hanging there so going to remove all non used wires also connector to bulkhead as not in use is that correct?

[Pete in NH]

Hello and welcome to the group,


While you are looking for the short circuit connect a tail light lamp or some other small 12 volt lamp between the positive battery cable and the positive post on the battery. If the lamp lights the short is still present. The lamp will limit the current available in the circuit so you don't risk more melted wires or a fire.

[myk]

If cost is a concern and you think the wiring is that badly damaged, then look to replacing it with an aftermarket wiring harness.  It will certainly be cheaper than a "correct" wiring harness but will work just as well, not cost you as much, and will keep you from burning the car up...

[Dino]

I used to stay away from electrical, basically because I didn't know anything about it.  With the massive help from members here, Pete in particular (thanks Pete!  ), I now actually enjoy electrical work.  In all fairness, the work we need to do on these cars is not that hard.  You're basically just tracing and checking wires.

After doing the test Pete mentioned I would remove the engine harness bit by bit, I'm not savvy on 3rd gens so my apologies if this doesn't make sense.  

On a 2nd gen you can just undo the bulkhead connector clips and remove the other ends of the wires.  On your workbench you can do a visual check for damage and measure resistance from end to end.  That will tell you a lot and will make it easier to decide what route to go.  Buy new or replace.  I was lucky in that I had very good wiring and only a few wires here and there needed replacing.  Actually they just needed insulation, but wiring is cheap enough if you can make it yourself.  

Just do it one step at a time and see what you find.  Do you want to keep the car stock?  If not, there's some easy upgrades to do to protect the car such as a maxi fuse between the battery and the cabin.

[Lewis]

Thanks for the help guys much appreciated! It's not so much the cost it's just the import, like I don't want to pay $159 ish for a cheap loom when I could get a better one and pay the same import if you know what I mean, also would you say a second hand wiring loom taken out a car same era is trust worthy or would people recommend buy new when it comes to wires?

Well I was heading down the keeping it stock route but it all depends on being cost effective and what's best for the car as I know there are some perfect parts out there that are aftermarket, also it has a custom built 383 in it that was built from bottom up, which the 73 didn't have the option of a 383 so you could say it's not stock so it's not a big deal if the car isn't stock, I do want the stock colour though haha top banana/ lemon twist 

[Pete in NH]

Lewis,

Finding a used wire harness is often not the best solution as it too will be 40+ years old. The engine wiring harnesses get baked by engine heat for years and suffer from exposure to grease and oil. An under dash harness will often be in better condition but, the plastic wire insulation does become brittle with age and all this plastic insulation becomes prone to cracking.

I think the best option would be a new reproduction wire harness for both engine compartment and under the dash. If you're tax situation there makes that cost prohibitive wire harnesses can be made if you learn some of the tricks of making them. All in all though, is  often less costly here in the US to but reproduction harnesses by the time you buy the materials. Your situation may be different.

I would start with carefully studying the wiring diagrams, you can buy bulk head connector pins and reusing the bulk head connector bodies if they are in good condition. It would help a great deal if you can post some pictures of the wiring in the car. It will then be easier to advise you on what direction to take.

A final thought on the universal wiring harnesses sold- They are not as easy to install as the makers would like you to believe and call for some good working knowledge of electrical wiring and testing.

[nascarxx29]

Take one wire at a time.power distribution starts at battery thicker wire heaver load .its a road map of where it starts and stops.

[Lewis]

Okay, little more investigation and it's the alternator wire that is burning out, so I spent a little time observing the alternator and following the wires and the thick wire from the alternator runs directly to the negative on the battery! Just to add its got an internal regulator on the alternator well I think just because I haven't got a voltage regulator on the firewall! Getting there bit by bit appreciate all the help thanks people!

[Pete in NH]

Please double check that, the output of the alternator should go to the POSITIVE terminal of the battery. You may be looking at a ground wire someone added if it goes from the case of the alternator to the negative battery terminal. It sounds like the electrical system may have been heavily modified from the way it left the factory. In any case alternator output to negative battery terminal is just plain wrong and has likely damaged the alternator if it is truly wired that way.

[nascarxx29]

We need pictures bolt on alt connection heavy red + If it was reversed battery and electronics to ground should be looked at.If you had reverse polarity

[Lewis]

Okay I can get pictures tomorrow sorry the cars not with me right now, in had an engine change and I gather the wires have been mixed up by accident or someone not knowing what they are doing, I have a couple pictures I can post of the bulk head and other bits for now till I get clearer ones for you tomorrow, also I have a msd 6al box and the wire from that goes straight to the positive, just trying to figure out why I have so many wires on the battery terminal!

[Dino]

I can't believe that poor car didn't turn crispy already!  Just leave the battery disconnected and get the pictures uploaded before you do anything else.

[Lewis]

It's not letting me post any photos at this moment I'll try again soon, I know i was panicking when it nearly set alight, waited 3 months for it to turn up!

[Dino]

Yeah that's scary stuff.

In order to post pics here they have to be less than 200 KB in size and have a unique name.  Alternatively you can upload them to flicker or photobucket or something and post the link here.

[Lewis]

Ah okay I get ya, I'll give it a go

[Lewis]

/ I've added a couple of photos of the wires just so you can see the state its in haha https://www.flickr.com/photos/134173939@N07/?

[Dino]

Uninsulated, non stock connectors galore here!  The first pic shows a stock connector but obviously you have some serious resistance issues in these looms.

I hate to say it, but all that will have to go, the lot. 

I understand that import duties are an issue, former Belgian here, but new wiring is the way to go.  Are there any ways to reduce or circumvent the duties that you know of?  I used to have parts shipped to someone in the US who then repackaged them as gift so I only paid shipping, but that may no longer fly these days.   

You could also find a local company that can make the wiring for you, but with hourly wages being what they are you may end up paying even more.

You "can" make your own wiring but I don't recommend that's how you start your first electrical job.

[Lewis]

Okay I knew it had to go I was just tying to make it work at least once so I could hear the engine as I have never heard one before yet own one if you know what I mean! Yes there is a way, I could get it chipped to my work as we buy from big suppliers so I'll have to speak to my work and see if I could get it put in there with there bits! I'm going to insulate Al the wires it was just a temp fix till I know what the major cause is which I gather may be the alternator