[AT] tractor electrical question

John Hall jtchall at nc.rr.com
Thu Aug 26 14:13:45 PDT 2021


It appears this operates in the same way.

John


On 8/26/2021 2:58 PM, deanvp at att.net wrote:
>
> I am not familiar with the I/H Farmall tractors electrical set up but 
> on JD’s 20 and 30 series JD Two Cylinders, 1956 to 1960, JD inserted a 
> dropping resistor that was bypassed during starting to give a full 12 
> V to the points and then when the starter was released it dropped back 
> to 6 V to extend point life.  But when things don’t make sense it 
> usually comes down to a bad connection somewhere.  Starting with grounds.
>
> Dean VP
>
> Snohomish, WA 98290
>
> "Socialism is a philosophy of failure, the creed of ignorance, and 
> gospel of envy, its inherent virtue is the equal sharing of misery."
>
> ..Winston Churchill...
>
> *From:* AT <at-bounces at lists.antique-tractor.com> *On Behalf Of *John Hall
> *Sent:* Wednesday, August 25, 2021 9:01 PM
> *To:* at at lists.antique-tractor.com
> *Subject:* Re: [AT] tractor electrical question
>
> 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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