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This happen to anyone else? I was driving my 72 on what was likely one of the best days of the summer. Put a ton of miles on the car that day. However, at the end with 1 mile to go to get home I started smelling burning plastic, then saw smoke. I pulled over and shut the car off and the smoke stopped. But when I started the car again it started smoking again. After having the car towed I found this (see pics). Previously I had replaced all the wiring in the engine bay due to the hacked original harness while installing a Chapman lock (a previous owner). Fortunately none of my new wiring burned. But this resistance wire smoked from the fuse box to where it meets at the steering column. After tracing I see it runs to the brown wire at the alternator. Taking a look under the dash it looks like there was some hacking done there to, aftermarket stereo and what looks like caps to prevent noise. As I start investigating to find the root cause I find more surprises.
Notice that two red wires are joined together? Hmmm...
Why the splice here off the door plunger?
Cap for noise
Where the burning stopped, thank god.
I then discover that someone put a 42A alternator on this car which has an aftermarket stereo and AC?
Bummer! but at least you did not lose the Corvette to a fire. I suppose this is why my friend said to install all new wiring in these old cars, not that I have done that, but maybe I should reconsider.
take those old Capacitors out, they can, and may have shorted out.
40 year old caps, dry out and fail. not really required with modern radios.
you will have to either get a replacement resistance wire,
or just ust use a resistor to replace for the ignition system,
check over all other wiring really good to ensure no other melted wires down the road, those pink wires tied together may be factory.
take those old Capacitors out, they can, and may have shorted out.
40 year old caps, dry out and fail. not really required with modern radios.
you will have to either get a replacement resistance wire,
or just ust use a resistor to replace for the ignition system,
The resistance wire cannot be soldered, so easiest fix is as 69vett says to use fixed resistor. But, I would look at what was causing it to fry in the first place.
Or "while I am at it" go solid state instead of points....
I think 42 amp is correct on the alternator for a non AC car.
I had issues with my resistor wire getting so hot I could not touch it and noticed it smoking one day. Had visions of breaking down or worse catching on fire. The Connections on both ends were clean. I could not find the resistor wire by the length for purchase anywhere, and you cannot solder in a replacement.
Decided to go the Pertronix III route that needs full 12 volts. Like Mikem said. The resistor wire is needed for the stock points set up. I tapped 12V power from the IGN connection in the fuse box. My future plan is to remove the resistor wire and tap into the harness block at the firewall.
I'm getting a cleaner burn with the Pertronix. I found it easier just to pull the distributor to swap in the Pertronix.
No, never happened to me. When i had my dash out the original harness looked like new probably because its protected from heat and sunlight. But i did replace my decrepit engine harness.
Good catch and thx for sharing. Are u going to just rewire what u got or replace the entire dash harness. I think u will need pin removal tools to get the connector pins out but it can be done. BTW the way the resistor wire is on the engine side of firewall and IIRC it's only 1.3 ohms. Yes, 1 point 3 ohms. Sorry but i'm thinking those burnt wires are on the inside/under the dash. One more suggestion is remove your drivers seat before you hurt your back working upside down. That way u can lie flat with legs in the baggage area.
I'm not sure why you have resistance wire in the passenger compartment area. The resistance wire should only run from the bulkhead connector at the firewall to the coil terminal. Also, wrapping that wire with others would assure that the heat generated by that wire could not be dissipated. Resistance wire should be open to the air so that it does not overheat.
So, I'm confused about the wiring system you have and how resistance wire got into that bundle. It's very good that no fire resulted; but correction (not just repair) is required.
Okay, I'm confused. The OP says that the burned wire leads up to the brown wire at the alternator, but there's several posts here about the ballast resistance for the ignition circuit. ?????? I don't see the connection (literally or figuratively).The brown wire at the alternator is either the system voltage sense wire, or the current feed wire that energizes the rotor field during cranking and low RPM (which I believe has a resistance in the harness).
Gm uses a resistance wire (for points only) from the bulk head connector in the engine compartment only,
the connection changes into regular wire inside the car going to the ignition switch.
A ballast resistor is commonly used in Mopar's, instead of a resistance wire.
so if you don't have a resistance wire, you can substitute a ballast resistor for it.
Gm uses a resistance wire (for points only) from the bulk head connector in the engine compartment only,
the connection changes into regular wire inside the car going to the ignition switch.
A ballast resistor is commonly used in Mopar's, instead of a resistance wire.
so if you don't have a resistance wire, you can substitute a ballast resistor for it.
That's not an answer to my question. Nevertheless, I'm still confused why you are talking about ignition wiring when the OP says the burned wire goes to his alternator. I'm not seeing where you're making the logical or electrical connection.
My understanding of the OP's description of things might be incorrect, but give me some detail so I can figure out where you're coming from.
Guys thank you very much for chiming in. I am trying to understand what happened. I have only slightly started to investigate as this weekends hot and humid weather was a deal breaker. Upon taking stuff apart the tracing of the burned single strand wire pointed me to the alternator wire after examining the pinouts on the engine harness and the fuse box. Factory or not, it is true that this burned single strand wire is in the dash harness. Once I get the drivers dash pad out so I can get a good look I will hopefully have more answers. Again, I appreciate all the input.
Also. My car is an original AC car. Should have the 61 amp alternator. Whose idea it was to put a 42 amper in there is beyond me. That I will sort out as well. When I bought this car a few months ago little was known about its history as it sat for over 10 years and the owner had passed away. So I am learning about it and correcting things as I go. I will say that after going thru the basics to get it road worthy the car runs very well, when it's not starting on fire.
And I did recently just put a new set of points in the car. Hmmm.
your gonna have to break out an ohm meter, and schematic.
that wire will need replaced, something shorted out to gnd.
and it basically goes only to the coil, then thru coil to points , one of them must have shorted out, is my best guess.
routing sounds correct, +12 key on ignition to bulkhead, changes to resistance wire going to the coil. Before you connect battery , make sure everything is 100% correct.
No that is incorrect for a 69 Harness, only the orange wire should be connected.
you need a schematic, on my 69 harness only the Orange wire is connected.
according to my harness that wire has been added to the orange,
the fried wire you show exiting the bulkhead firewall into interior is brown on my assemble.
No that is incorrect for a 69 Harness, only the orange wire should be connected.
you need a schematic, on my 69 harness only the Orange wire is connected.
according to my harness that wire has been added to the orange,
the fried wire you show exiting the bulkhead firewall into interior is brown on my assemble.
Do you happen to have a pic of the ignition switch connector housing like the one I posted showing the crimp on the orange wire? I'm curious as to what an original looks like which is routed correctly. If the brown doesn't crimp to orange then where does it go? There are only two pins in the housing for the ignition switch.
my ignition switch connector looks exactly like yours, with only the Red and Orange wires,
minus your fried wire. ( it appears that fried wire was added in)
My harness is an old parts harness, it could be missing a few wire connections.
but it appears original in this area.
I had the exact same thing happen on my Triumph. replaced the resistance wire with a ballast resistor from a Chrysler product and never worried about it again...glad you caught it!
07-23-2016, 11:16 AM
1972 - Resistance wire burns at fuse box. Ugh.
