Bad Ignition Switch???

Bob Kirk · Nov 25, 2008

My 1955 IH 300 utility has been known for starting first time every time. But lately, including today, it has failed to fire at all after sitting for a week or two. I have replaced all ignition parts including the coil, but today again there is no "pop" at all.

But as soon as I hooked a hot wire from the positive side of the battery to the positive side of the coil, she fired right up.

Something in the back of my mind tells me that this means the ignition switch is bad or I have a bad wire between the switch and the coil.

Is this correct? Can I identify which wire runs to the coil just by looking at the back of the switch?

This tractor is 12 volt, negative ground. It has some kind of ceramic gizmo mounted on top of the coil that the positive side wire goes in and out of -- I think for regulating voltage to the coil? Could this gizmo be my culprit?

By the way, is there any downside to running the tractor temporarily with a hot wire from the battery to the coil?

Thanks very much for your thoughts. Bob

El Toro · Nov 25, 2008

You need to use a volt meter or test lite to check for voltage at the coil with the ignition switch on. That may be a ballast resistor on your coil for dropping the battery voltage from 12 to 6 volts to the coil.

If there's no voltage at the coil you need to trace that wire from the coil back to the switch.
Once you find where the wire is connected on the switch use your volt meter to see if there's battery voltage where that wire is connected. Your switch still needs to be on. If there's voltage at the switch you need to run a new wire from the switch to your coil. Hal

Janicholson · Nov 25, 2008

There are three possible issues. El Toro has two of them covered. The third is that the Ballast resistor (ceramic gizmo)is bad. It is more than likely needed. and can be replaced easily from Chevrolet vehicles late fifties to late sixties, of similar Chrysler vehicles. It does the job as described, and is cheaper than a coil that does not need one. It will possibly ruin the points or coil to run with out. JimN

Dellbertt · Nov 25, 2008

What you did not state is whether you jumped the positive to the coil before or after the ballast resister. Try it both ways so you can eliminate the resister or not. If it fires from pos bat to coil before resister then its probably an intermitent switch. If it only fires pos bat to coil bypassing the resister then it"s prob a bad resister.

Dellbertt · Nov 25, 2008

Jim answered while I was typing, I think you have all the bases covered now.

Bad Ignition Switch???

Bob Kirk

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El Toro

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Janicholson

Well-known Member

Dellbertt

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Dellbertt

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