Farmall Cub

I am having a battery drain on my farmall A. I thought at first it was a bad switch but that does not appear to be the problem. As soon as I hook up the battery cable up to the the starter (with the switch off) the amperes gauge shows a very slight discharge. I can not figure where the problem is. I put a new wiring harness on the tractor a couple of years ago as well as new battery cables. Any ideas?

Systematically disconnect electrical components until you find the culprit. Why are you sure it's not the switch?

My first guess would be that either your ignition switch is on, or bad and staying on all the time, or that one of the contacts in your voltage regulator or cutout, depending on which you have has stuck shut.

Don McCombs wrote:Systematically disconnect electrical components until you find the culprit. Why are you sure it's not the switch?

I checked the switch for continuity which checked the same as a new switch I had bought but never put on because I liked the looks of the original. Doubting myself and the test I put the new switch on the tractor givinig the same the same results.

I will do as you suggest but I do not understand what could be shorting out if nothing is turned on. What should I start with? Contacts in the regulator look OK.

John *.?-!.* cub owner wrote:My first guess would be that either your ignition switch is on, or bad and staying on all the time, or that one of the contacts in your voltage regulator or cutout, depending on which you have has stuck shut.

Swtch is off. I checked the switch for continuity (was the same as a new one) and then changed it anyway because I had a new one.


As soon as I attach the cable to the starter I see a very slight discharge on the amperes gauge. The contacts in cutout look good (I cleaned them anyway) and do not appear to be sticking. The cutout was new also and has been working. I will try disconnecting one wire at a time tomorrow.

Example of what I have.
http://brillman.com/store/o-voltage-reg ... touts.html

Unhook the battery wire going to the regulator

Boss Hog wrote:Unhook the battery wire going to the regulator

Will try that tomorrow. If that elimates the discharge I will need to know what it means and the next step. Thanks!

Boss Hog wrote:Unhook the battery wire going to the regulator

I did that and the amperes gauge went back to 0. No more discharge that shows.

I took the cover off of the reulator/cutout. As it was sitting contacts were open.
When I closed the contacts the generator started turning. When reopened it stopped so those contacts are not sticking.

The other set of contacts are spring loaded in the open position and work freely.

With the battery wire going to the regulator disconnected, what will not work?

I need to know what this means and the next step. Thanks!

Just trying to get the tractor to a show next weekend.

Regulator. What's malfunctioning is the cut out portion of the regulator is supposed to disconnect the battery from the generator when the generator output voltage is low.

With the battery wire going to the regulator disconnected, what will not work?

Obviously the generator will not charge the battery. Could also be the ignition and lights will not work - depends on how the tractor is wired.

I need to know what this means and the next step.

My next step would be to purchase a regulator. Depending on the regulator mount, it may be available from your local auto parts store. Several advertisers carry the saddle mount regulator.

Tip: When you dismount the regulator. Label each wire as you remove it with the letter stamped on the old voltage regulator wire terminal.

Eugene wrote:Regulator. What's malfunctioning is the cut out portion of the regulator is supposed to disconnect the battery from the generator when the generator output voltage is low.

With the battery wire going to the regulator disconnected, what will not work?

Obviously the generator will not charge the battery. Could also be the ignition and lights will not work - depends on how the tractor is wired.

I need to know what this means and the next step.

My next step would be to purchase a regulator. Depending on the regulator mount, it may be available from your local auto parts store. Several advertisers carry the saddle mount regulator.

Tip: When you dismount the regulator. Label each wire as you remove it with the letter stamped on the old voltage regulator wire terminal.

That is what I was afraid of. I was hoping there was something less expensive that I was missing. The regulator on it is not very old. I had the generator rebuilt and bought a new regulator about 5 years ago. Hopefullly it is just a faulty wire. It is a saddle mount by the way, not hard to find.

Thanks for your help!

I have seen a few generators that were shorted out ,

Boss

Boss Hog wrote:I have seen a few generators that were shorted out ,

Boss

I have them short out also. It just seems that the symtoms are not consistant.

Thanks for your help!

Oldman1151 Stated:
That is what I was afraid of. I was hoping there was something less expensive that I was missing.

Check this out: http://www.farmallcub.com/phpBB2/viewtopic.php?f=1&t=72180

I had the generator and regulator/cutout checked today. Diagnosis is that generator and regulator/cutout are both good. Looks like the problem may be in the 4 position light switch (low charge, hidh charge, low beam, high beam). This switch is hooked up to the "L" terminal on the regulator/cutout. When this "L" wire is disconnected and the BAT wire is connected there is no drain on the battery. When the tractor is running the generator charges as it should. I guess this narrows the problem down to the light switch or something connected to it inside the switch box. I may not get into that until our tractor show is over.

At least the more expensive components are good, the tractor runs and charges like it should and I learned something.

Thank you to everyone for your help.

The original cut-out would not have had an L terminal. You have a later style regulator that does not require the 4 position switch to control charge rate. If your L terminal is connected to the point the generator F is normally connected, that is your drain. Do your lights work with or without the L terminal connected to anything?