Riddle Me This

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J

jhawk

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I'm tuning my carb this morning and when things are about perfect the car shuts off. I try and restart it and it fires up, a second later the car fills up with electrical fire smoke and dies. Once the smoke cleared and I got under the dash the black wire going to the flasher is toast, insulation burned off all the way up as far as I can see. I pull the flasher down, make sure none of the exposed wiring is hitting anything and the car fires right up and runs. I'm assuming it grounded out against something and while cranking the car over it became part of that circuit. Thoughts before I dig into it tomorrow?

Thanks,
Jim
 
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When a wire melts, especially in a bundle, it is likely wires melted together.

It will be hard to find under the dash.

Good luck
 
If the wire with melted insulation is in a bundle, it means THAT wire got so hot that the insulation melted. It also means another wire in the bundle got hot enough to burn off the insulation & the exposed copper of of both wires came into contact & cut the engine. Cause of melted insulation is excessive current, eg a short cct.
 
It helps immensely if you post what you are working on.
Looking at your older posts, its a '69 Dart.
Go to mymopar.com and download the service manual for '69. If you can read a map you can read an electrical diagram. It will show you what the black wire is and what it connects to and from.

Should be simple depending on the options with your '69. The flasher circuit isn't fused. The flasher unit itself acts as a circuit breaker. So a short downstream of the flasher should have simply caused the turn signals not to work. A short on the feed means current was being diverted from the alternator to ground (assuming the car was running).

Turn signal flasher is a branch off the accessory feed. It only is connected to power when the key is in accessory or run positions.
1725282565145.png


Switched Accessory Q2 feeds 4 branches, so they're all bundled together. But D1 to the flasher is probably bundles with only itself, feeds to the radio and radio lamp, and wires to the right side door switch.
1725283166076.png


This '69 valiant but dart is probably same for this.
1725283988165.png


When hunting the problem, look for where the wires were rubbing. It might be mice but it also might have been the wire routing or support got messed with at some point. Ohm out the flasher unit to make sure it didnt ground internally. Seems unlikely but if you dont see another cause..

The options that can make it a bit more complicated are the in the 'light' group.
www.forabodiesonly.com

light group wiring harness

I have a 69 Dart 340 swinger. I am looking to add the interior light group to my car. I have all the lights, glove box, ash tray, map, and ignition light. Looking at the wiring diagrams, it appears to have a harness that connects all these lights together. Is this true? If so, how can i find...
www.forabodiesonly.com www.forabodiesonly.com
 
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One of my favorite methods, AFTER you find what you think you've found to be the trouble, is to PROTECT the system while you look for further shorts. To do this, get a large wattage 12V lamp. Headlight, or tail/ stop lamp or maybe two of those wired in parallel. Now put your protection lamp in SERIES with the battery ground. Make certain everything you can find in the car is OFF. If the lamp is lit, remove fuses and watch for change. If it is STILL lit, try disconnecting things like the alternator output wire at the stud on the alternator. Use your head.

Wires get melted in the harness and cross together. It can be a nightmare. If you judge this as fairly severe, I would pull the harness, lay it out on a table, nail/ tie it down so you can locate the branches and then unwrap it. Tie the branch points so you know where to re-wrap them.

There are quite a few things in the original cars that ARE NOT FUSED other than the main fuse link and it is POOR PROTECTION
 
An annoying story from the old days. In the early 70's, stationed at NAS Miramar, I had a 70 440-6 RR bought from a friend. (We still are to this day). Some girls in a Datsun A-holed the car while stopped in traffic. I had two different (junk) Valiants loaned to my by McCune Chrysler Plymouth, the HACKS that "fixed" the RR. Anyhow, one cold morning (yes) at the RADAR shop, I went out and started the loaner to warm it up

My Chief arrived, who did a perfect rendition of the Detective in "Columbo." He came in the shop, knitted his eyebrows in deep concentration, and said, "I just have one question? Is it supposed to be squealing and smoking?"

So I went out and discovered the alternator had locked up. What I DID NOT KNOW is the REASON. I got a rag, loosened the belt to examine, and when I did, THE DIODE THAT HAD FALLEN OUT OF IT'S MOUNT, AND DOWN INSIDE, SHORTED. I got to watch the ENTIRE UNDERHOOD harness go PHIZZLLE--fiZZZZ ZZZZZ ZIP!!! and right before it quit, the FUSE LINK blew!!!

The fuse link is POOR protection!!!
 
I'm working on a 69 340 auto Dart. Thanks for all the responses, ideas and schematics. I'll dig into the car a little more today and keep everyone posted.

Jim
 
The black wire(which I believe is ground) from the flasher has the insulation melted off of it up into the main harness about an inch. It some how managed to not do any real damage to anything but itself into the main harness. The power wire and wire to passenger side door have some melted insulation but not into the copper. I opened up the flasher and it seemed fine. I'll wire in a new flasher this weekend and update things.

Let me know if you have any other ideas, or input.

Jim
 
In automotive wiring BLACK does not mean ground. In fact Black IS. a main power feeds.

At the ammeter there is a Black AND a Red. One goes to the alternator, one goes to the battery. Both are 12v.

You need to follow and trace out all cirs from battery / alternator to ground. Ground is typically the car body.

There are exceptions like the dome light cir which runs a wire from the door switch (which grounds out when you open the door)to the bulb, then from the bulb ultimately to a power source.
 
So it turns out the wire from the ignition switch to the starter relay was I believe, the main issue. At one point in time the wire that goes into the bulk head was replaced with a smaller gauge wire which burnt though and shorted out also. Installed new terminals in the bulk head connector and ran a new appropriate gauge wire to the starter solenoid and all is good. Thanks again for all the help gentlemen.
 
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