[AT] tractor electrical question

[Carl Szabelski]

https://www.yesterdaystractors.com/cgi-bin/viewit.cgi?bd=nboard&th=366678

https://www.hemmings.com/stories/article/ignition-coils

Did a quick search and found these two links. Hope they help to understand
how coils function.

Carl

On Thursday, August 26, 2021, Howard Pletcher <hrpletch at gmail.com> wrote:

> I would concentrate on the coil first.  Defective new ones are not unheard
> of.  Have you got another vehicle--tractor or car or truck--that you could
> swap with. Any that has 6V to the coil when running should work.  If it
> won't fit your mounting, just secure it temporarily, be sure the case is
> well grounded, and see what happens as it runs for a time.  And you can
> test the one from the tractor in the donor vehicle.
>
> Howard
>
> On Wed, Aug 25, 2021 at 11:54 PM John Hall <jtchall at nc.rr.com> wrote:
>
>> Ordered coil from CaseIH by the parts book is all I know. I have the same
>> issue with either coil. After reading about ignition systems, it seems
>> resistors are used in a different circuit for once engine is running,
>> voltage is dropped so as not to burn points. 12 volts are sent for cranking
>> only. I'm wondering if there is a resistor somewhere thats failing when it
>> gets hot?
>>
>> John Hall
>>
>>
>>
>> On 8/25/2021 11:21 PM, Howard Pletcher wrote:
>>
>> Is that the original coil?
>>
>> I'm not familiar with the 454, but in the truck world, most coils are
>> intended for 6V use.  There is a resistor wire in the harness that drops
>> the voltage while the current is flowing with the points closed.  But there
>> are also coils intended for 12V use with no resistor wire.  If that is not
>> the original coil, perhaps you have the wrong one.
>>
>> Since it seems to work fine with 12V applied, I'd probably run another
>> wire from the ignition switch to the coil to bypass any possible resistor
>> wire.
>>
>> Howard
>>
>> On Wed, Aug 25, 2021 at 11:08 PM John Hall <jtchall at nc.rr.com> wrote:
>>
>>>
>>> If there is, I can't find it. Closes thing I have found is the
>>> diode/rectifier for the alternator. Its inline and is tied in on this
>>> particular "circuit" . Matter of fact, the side opposite the alternator
>>> is where the fuel solenoid feeds from.
>>>
>>> John Hall
>>>
>>>
>>> On 8/25/2021 11:05 PM, Spencer Yost wrote:
>>> > Maybe there’s an external resistor?
>>> >
>>> > Spencer
>>> >
>>> > Sent from my iPhone
>>> >
>>> >> On Aug 25, 2021, at 10:35 PM, John Hall <jtchall at nc.rr.com> wrote:
>>> >>
>>> >> Got what I hope is a simple question. On my IH 454 tractor, is the
>>> voltage going to the coil a constant 12V? I'm having some issues with it
>>> running bad when it gets hot (I've already replaced everything but the plug
>>> wires). Found out today that if I run a jumper wire from battery to the
>>> coil, the problem goes away. Take it off problem comes back, put it back it
>>> goes away, take it off, it comes back. So I am tracing the wiring but this
>>> one isn't simple, new enough there are tons of gauges, fuel solenoids,
>>> safety switches, etc. Anyway, if I check voltage at the coil, the fuel
>>> solenoid, and there is one small terminal on starter solenoid that all read
>>> 12V if the switch is on. If I bump the engine over slightly (I guess the
>>> pts are closing) then the coil and starter drop to just under 6V, fuel
>>> solenoid stays the same. So shouldn't there always be 12V at the coil?
>>> >>
>>> >> John Hall
>>> >> _______________________________________________
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>>> >>
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>>
>>
>> --
>> Howard
>>
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>
>
> --
> Howard
>
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