[AT] tractor electrical question

[John Hall]

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 
> <mailto: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
>     <mailto: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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> -- 
> Howard
>
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