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MikeP
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wiring harness
07/29/19 at 16:27:00
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so the other day i added water to my radiator to begin the flushing and stuff and so i put the cable on the battery so i could cycle the water through and when i pushed the started rod it started smoking so i quickly pulled the battery cable off and saw some sort of fabric wrapping on fire above my starter so i put it out and then saw the wire that goes from the starter to i believe the ammeter is now burnt in half so i think its time to replace it

now my question is what is the difference between a cj3a harness with turn signals vs an m38 harness both 12v harness's and would i be able to use the light switch of an m38
  

1950 willys cj3a
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Rus Curtis
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Re: wiring harness
Reply #1 - 07/29/19 at 21:27:15
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Mike,
Sorry to hear about your wire.  Good that you can move fast!

Using the Service Manual (SM) diagrams, I've compared my 3B harness to the 3A.  At the starter it seems very similar.  The only real function I see to that wire that goes to the Ammeter is so it can register Amp draw (negative when you hit the starter rod and positive when the engine is revved). 

On both, that terminal on the back of the gauge shows just 2 things connected:  The + wire (after passing the starter) and the horn (it needs to be hot always vs. switched). 

The other terminal should have a wire that runs to your ignition and the other wire to the regulator.  All wires need to be insulated from the clip that holds the gauge up against the "dash."

It may be possible there was a grounding on that wire.  It may be possible the starter pulled too many amps and overloaded the wire.

Before you disconnect, using an Ohm meter, check to see if you have continuity from the end of the burnt wire to the metal body, i.e. the bracket holding the gauge or the back of the dash somewhere on bare metal.

You may want to test the starter (I'd take it to a shop so they can put it on a machine).
  

'54 CJ-3B "Green Gruntt"
Bantam T3-C
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MikeP
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Re: wiring harness
Reply #2 - 08/04/19 at 21:35:47
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well i tried to start it today and found out that the only wire coming from the starter into the dash/ammeter (my fried wire) supplies voltage to the rest of the equipment including the coil and so on so it was never gonna start unless i tied it back together

also what gauge wire would i use to make a quick replacement

i also asked kaiser willys about the harness differences and got this

Question: im in need of rewiring my 6v 1950 cj3a to 12v but im also in the stages of putting an m38 tub on my frame and converting it to be an m38 jeep so my question is what is the differences between this wiring kit vs a cj3a wiring kit

Answer: The M38 harness in 12 volt and CJ-3A harness are going to be basically identical to one another.
  

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Rus Curtis
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Re: wiring harness
Reply #3 - 08/05/19 at 11:01:58
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You're correct on the flow from the ammeter supplying the rest of the vehicle with juice.  The ammeter must be in in line so you can see drain/charge cycles.  The light switch has a breaker so if there were a short, all circuits after that would be isolated when the breaker opens.  The ignition circuit isn't connected to that breaker.  It goes from the ammeter to switch and then directly to the coil etc.

I found out that some vendors order harnesses from Vintage Wiring and then sell under their name.  I personally went with a Vintage Wiring harness and their support is unrivaled.  I got lots of help. 

The difference in wires between voltages is a 6V typically has larger wires to avoid restricting flow (not sure about all wires but the battery cables are bigger).  12V wires can be smaller.  I didn't know an M38 was 12V (I would have assumed 24V) but from this perspective seems irrelevant; you aren't doing a military vehicle restoration.

I'm only guessing but a 12 or 10 gauge wire should work.  Before hooking it up, you may still want to figure out why it burnt - to avoid repeats.
  

'54 CJ-3B "Green Gruntt"
Bantam T3-C
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MikeP
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Re: wiring harness
Reply #4 - 08/05/19 at 12:02:53
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an m38 starts its life as 24v and most convert to 12v in my case i have a 50 cj3a that is 6v but will eventually go to 12v but im currently adding an m38 tub and gonna make it look like an m38 but the holes on the firewall are different than a 3a so i might need to choose the m38 harness to match the layout

and the reason for the fried wire was the cloth wrapping on the wire was coming off and the pressure washer pushed the bare wire against the starter pedal rod and well when the pedal was pushed and electricity was created stuff smokes and melts lol
  

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Rus Curtis
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Re: wiring harness
Reply #5 - 08/05/19 at 19:24:05
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Good.  Sounds like you know where it began.  A wire replacement should fix you up!
  

'54 CJ-3B "Green Gruntt"
Bantam T3-C
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