Electrical Short

[Gary Puckett]

I just want to verify that if everything is correct with the wiring, ignition switch in the off position, light switch in the off position, that there should be no voltage reading between the positive post and the ground cable (disconnected). On my 59 Cub, still 6 volts, positive ground, I get a reading of 2.85 volts. On my H Farmall, I get 0 volts. This seems like an electrical short to me. Am I correct?

[Eugene]

Terminal to terminal battery voltage was? Discharged or bad battery?

The voltage drop on the ground, with all switches off, should be zero or very close to zero volts. 6.5 volts, battery voltage, minus 2.85 volts, indicates approximately 3.65 voltage drop. Significant.

Disconnect one electrical appliance at time trying to disclose the offending circuit. Start by disconnecting the voltage regulator.

[Gary Puckett]

Thanks Eugene, for the response. Brand new NAPA battery- terminal to terminal 6.5 volts fully charged not connected to tractor

[John *.?-!.* cub owner]

With that reading, there is something with very high resistance allowing current to pass. Since most digital voltmeters have an input resistance of 10 meg ohms or more that would indicate your short would be in the range of 7 meg ohms give or take a little, since your meter and whatever the short is are forming a series circuit. That could be dirt or carbon in or on the end of the ignition switch, head light switch, or regulator. Or could be a cable with crack insulation and dirt or oil in the crack. The only way to find it is going to be as Eugene said, start disconnecting leads. If I remember correctly your tractor would have a regulator on the top of the distributor, and the first place to start would be to disconnect the L lead on the regulator. It provides power to the lights and ignition. If it goes away you need to look at the light and ignition switches and the wiring going to them. If no help, disconnect bat lead from regulator if voltage goes away look for problems in regulator. If still have voltage at this point, check wiring from bat lead back to batt cable.

One other thing, if your voltmeter is auoranging, which most newer ones are, make sure that reading was 2.85V, and not 2.85mv.

If this is not creating a problem with draining the battery, I would not chase it much. With all this typing I am assuming you do NOT have anything electronic such as a tack, radio, or clock, etc. wired to it.

[Gary Puckett]

Thanks John for the time put into this answer. I will try these remedies in due time. There are no additional non-stock components, but who knows what is under the hood that I cannot see. The wiring may be original. It looks old and the sheathing dry and rotten. I expect my next job will be wiring. I have done it on four other tractors.