H 12 volt system

Farmall H, HV & Super H, 300 & 350, 1939-1958
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H 12 volt system

Postby kaleb58loboy » Mon Dec 04, 2017 3:39 pm

Acquired a 1945 H converted to 12 volt system
Delco alt,3 wire, and external ballast resistor.
Problem- the H runs great BUT will not shut off,
jerry rigged key switch that does nothing.
Believe none of what you hear
Half of what you read
All of what you see.

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Re: H 12 volt system

Postby staninlowerAL » Mon Dec 04, 2017 4:21 pm

Probably incorrectly wired. If the engine continues to run with the switch off, it's probably running on the alternator output. Try a search for the wiring diagrams.
Stan in LA (lower AL)
USAF & Reserves, Reg ARMY, ARMY NG (AL)

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Re: H 12 volt system

Postby Eugene » Tue Dec 05, 2017 6:07 am


2nd wiring diagram in above link is correct and should be used on your tractor.

The fault, engine runs after ignition switch shut off, is that the alternator is back feeding the ignition system through the #1 wire position on the alternator.

The #1 wire on the 10SI alternator needs to have a diode, or light bulb, or have a switch.
I have an excuse. CRS.

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12V with Petronix
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Re: H 12 volt system

Postby ShawnAgne » Thu Dec 14, 2017 11:10 am

When I converted the 350 and the Cub over to 12V the Cub did the same thing. I had the fuse wired incorrectly and it was bypassing the switch.
Shawn Agne

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