[AT] tractor electrical question

John Hall jtchall at nc.rr.com
Thu Aug 26 14:09:55 PDT 2021


They list 2 coils, I got the 396546r93, its almost double and what was 
in stock.

John


On 8/26/2021 9:08 AM, Jason wrote:
>
> The coil you should have gotten sb 396547r93. Which is a 12v internal 
> resistor coil.
>
> It's unlikely if you have the right coil, that both old and new are bad.
>
> Which leads to condenser, wiring, or ignition switch
>
> Jason
>
> On Wed, Aug 25, 2021, 11:00 PM John Hall <jtchall at nc.rr.com 
> <mailto:jtchall at nc.rr.com>> wrote:
>
>     There is a wire tied in from the starter solenoid also. You would
>     assume a new OEM coil to be good but who knows. All I know is it
>     acts the same with both coils. I will note that the new coil had
>     to be rotated 180 in the bracket to get it to hook up. The power
>     is going in the plus side, just like schematic shows. Maybe they
>     just put it in wrong at factory?
>
>     John
>
>     On 8/25/2021 11:52 PM, Jason wrote:
>>     Generally most coils have a resistor before them to lower the
>>     voltage so they don't burn up the points. Some applications have
>>     a booster wire from the small  terminal on the starter solenoid.
>>     Since there is a voltage drop when cranking, this booster wire
>>     temporarily raises the voltage to help during starting.
>>
>>     If everything else is fine. A coil that fails as it warms up is a
>>     coil getting close, to well, failing.
>>
>>     Jason
>>
>>     On Wed, Aug 25, 2021, 10:22 PM Howard Pletcher
>>     <hrpletch at gmail.com <mailto:hrpletch at gmail.com>> 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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