melting wires

V

vt nick

Junior Member
i am working on my boss' 29 tudor. we are in the process of fixing bad wiring and the like. i have done most of it and thought i got it all, but there was one circuit remaining. the brake lights. that open lead in the engine compartment that had eluded me. let me say now, that the previous owner did not have the original main harness with the wiring hub. all other wiring is to a nonoriginal, late model light switch in the cabin.
i looked at the wiring diagram, and saw that the brake light switch is wired through the wiring hub to the generator(green wire). so i connected the line side of the brake light switch to the generator directly(since there is no hub), load side going to the rear light. when i connected the battery to test, the wire going from the generator to the brake light switch smoked and melted, as well as the two wires from the terminal box to the ammeter. but no others. i'm at a loss. is it possible the switch is bad and created a short? but why would the ammeter wires melt too? can anyone help?
 
Here is the stock wiring Diagram;

WiringDiagram.jpg
 
I had a simular thing happen, but was quick to the battery disconnect and saved my wiring. Turns out one of the flag style wire ends had turned and grounded against the popout cable. Rod
 
thanks for your reply mike. the trouble is, i looked at that diagram, and all is well (except there is not main harness hub). instead of the green wire terminating at the hub and continuing to the generator via the yellow, i have the green directly wired to the generator. my assumption is that there is no break in that circuit at the hub, and direct wiring it would not be an issue. can you confirm or deny that?
 
It sounds like you have a wiring nightmare on your hands. The stop switch does not go to the generator, see Mike's wiring diagram and fix everything you can.

Once you let the smoke out of those wires they need replaced and possible the ammeter. The stop switch could also be bad. Since this is your 1st post, you do realize that this is a positive ground system.
 
vt nick said:
rod, what do you mean by the popout cable?
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The popup cable is the thick cable going from the ignition switch to the dist. You need to be very careful with all of the connections on the back side of the switch as they can ground out on the gas tank or other wires. I have plastic caps over all connections but you can also use electrical tape.
 
Hare are pic's of origianl popout ignition cables. These run from the switch to the distributor. Rod
 

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Keep in mind that this was my fault as I did not put the grommet in place where it goes through the terminal box. I will never do that again.

Honestly I think your problem may be in the tail light somewhere it it is wired anything close to origianl. Were your headlights turned on? Just some fuel for thought. Rod
 
I believe you are correct in your assumption that the problem is with the brake light switch. From the generator the circuit continues to the ammeter and then to the battery. Your short is overheating the complete circuit from the battery not just from the generator.
 
Jerry said just what I was going to say. And yes, it's very possible the brake switch is shorted to ground. Use an ohm meter or continuity tester to check the switch. Put one lead on the brake switch case and the other lead on one of the terminals. Pull the switch on and off and you should NEVER show continutity. Move the lead to the other switch terminal and repeat the check. Again it should NEVER show continuity.

If it passes these two checks, then put the two leads on the two switch terminals. Now pull the switch on and off and see if you have continuity ONLY in the on position.

If it was my car I'd buy a new correct stye harness and put the wiring back to the original Ford way. It doesn't cost that much to replace the wiring.
 
vt nick said:
the wire going from the generator to the brake light switch smoked and melted, as well as the two wires from the terminal box to the ammeter. but no others. i'm at a loss. is it possible the switch is bad and created a short? but why would the ammeter wires melt too? can anyone help?
Click to expand...

Yes it is possible the switch could be grounded, which would melt the wire between the switch and the generator. The wires from the ammeter, if they are a smaller guage, will melt also but the larger guage wires won't. The larger wires will get hot and melt eventually unless the smaller wire, acting like a fuse, opens and stops the current flow.

Tom, yer a faster man than I am. :D
 
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vt nick said:
instead of the green wire terminating at the hub and continuing to the generator via the yellow, i have the green directly wired to the generator. my assumption is that there is no break in that circuit at the hub, and direct wiring it would not be an issue. can you confirm or deny that?
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I can confirm that the way you described your wiring there is no issue. The hot side is hot whether it is at the ammeter, the battery, the generator or wherever. The only difference in location is which side of the ammeter. If it is connected before the ammeter it will not show a discharge.
 
Best thing to do is throw out all the jury rigged wiring and order a new harness from Snyders or Brattons and a new light switch before you burn the whole car down. There are wires in places that if they melt and touch, you probably couldn't get the battery loose fast enough to keep it from burning. Wiring and electricity are 2 things you don't want to rig. Especially since you have already let the smoke out of what you have.
 
It looks to me that there are a couple possibilities. A shorted brake switch,B ,Short in tail lights due to broken insulator or wire with defective insulation,C wire with bare insulation or pinched some where on the frame. An old trick I use is to rig a 6 volt buld such as a head light bulb with a couple of wires and alligator clips. Put this in series with the wiring you are having trouble with. I the bulb lights up to full brilliance you have a short, If it glows dimly your circuit is ok. The bulb limits the current so you can't burn anything up. I have used this trick for years on motorcycles,cars and even Ham transmitters with good luck.:)
 
A motion was made by Tom to replace the wiring.
The motion was seconded by James.
All in favor.
Aye.
 
By all means go back to the original style wiring& light switch.I also have a 30 amp breaker mounted on engine side of starter switch & 20 amp inline fuse holders for lights & horn.
 
Milton said:
A motion was made by Tom to replace the wiring.
The motion was seconded by James.
All in favor.
Aye.
Click to expand...

In lieu of that, if you just choose to replace wires, use Teflon covered wire. It does NOT burn or melt..Your appliances and switches may melt but the wire will be reusable.
 
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