I just realized I misspoke previously. I was looking at the diagram where it calls out the “cranking motor” and should have realized that the diagram is actually showing the connections to the starter coil. So your issue may be with the starter coil, not the starter itself. Don’t know if you can open up the starter coil to get a look inside at the contacts, on some you can. Try totally removing the starter coil and reinstalling it, making sure all connections are good and you have a good ground. And if you can get at the internals of the starter coil, try cleaning all the contact points. <div><br></div><div>Another check you can do first is similar to what you did with running a wire directly to the ignition coil from the battery. This time jumper from the battery connection at the starter relay to the terminal on the starter relay that goes to the coil. If the engine runs like it should then the only thing that is no longer in the circuit is the starter relay, and it has to be the culprit.<br><div><br></div><div>Carl<br><br>On Thursday, August 26, 2021, Carl Szabelski <<a href="mailto:c.s.szabelski@gmail.com">c.s.szabelski@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> By the way, I believe it’s not the coil and is related to the cranking motor. Especially since the voltage drops when you bump it like you said. Something in the motor may be partially shorted or corroded, causing a voltage drop to the coil. The coil should always see 12V whether or not there is a resistor, internal or external. The resistor is essentially after the coil winding and drops the voltage after the winding, not before it. If the engine is running fine when you directly connect 12V to the coil, the coil is working like it should and is good. <div><br></div><div>Carl<br><br>On Thursday, August 26, 2021, Howard Pletcher <<a href="mailto:hrpletch@gmail.com" target="_blank">hrpletch@gmail.com</a>> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:tahoma,sans-serif">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.</div><div class="gmail_default" style="font-family:tahoma,sans-serif"><br></div><div class="gmail_default" style="font-family:tahoma,sans-serif">Howard</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Aug 25, 2021 at 11:54 PM John Hall <<a href="mailto:jtchall@nc.rr.com" target="_blank">jtchall@nc.rr.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
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?<br>
<br>
John Hall<br>
<br>
<br>
<br>
<div>On 8/25/2021 11:21 PM, Howard Pletcher
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-family:tahoma,sans-serif">Is
that the original coil?</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">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.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">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.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"><br>
</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Howard</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Aug 25, 2021 at 11:08
PM John Hall <<a href="mailto:jtchall@nc.rr.com" target="_blank">jtchall@nc.rr.com</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
If there is, I can't find it. Closes thing I have found is the
<br>
diode/rectifier for the alternator. Its inline and is tied in
on this <br>
particular "circuit" . Matter of fact, the side opposite the
alternator <br>
is where the fuel solenoid feeds from.<br>
<br>
John Hall<br>
<br>
<br>
On 8/25/2021 11:05 PM, Spencer Yost wrote:<br>
> Maybe there’s an external resistor?<br>
><br>
> Spencer<br>
><br>
> Sent from my iPhone<br>
><br>
>> On Aug 25, 2021, at 10:35 PM, John Hall <<a href="mailto:jtchall@nc.rr.com" target="_blank">jtchall@nc.rr.com</a>> wrote:<br>
>><br>
>> 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?<br>
>><br>
>> John Hall<br>
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</div>
-- <br>
<div dir="ltr">
<div dir="ltr">Howard</div>
</div>
<br>
<fieldset></fieldset>
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr"><div dir="ltr">Howard</div></div>
</blockquote></div>
</blockquote></div></div>