Farmall H Wiring

Sun Mar 20, 2011 7:32 pm

I know there are numerous posts about this. I have looked ant any posts and diagrams, but cannot find one that illustrates exactly like mine. I have a 49' H, with distributor, 4-post light switch and voltage reg.

here is what I have:

1. a wire from the F term. on the VR to the F on gen.
2. BAT on VR to Discharge side of the gauge.
3. a wire from Discharge of gauge to the fuse lag on the light switch.

I know I have the wire for the lights correct, or at least I think I do.

Any help is greatly appreciated!

Re: Farmall H Wiring

Sun Mar 20, 2011 8:05 pm

It would help if we knew what was not working?

Re: Farmall H Wiring

Sun Mar 20, 2011 8:16 pm


lights do not work. I have not tried to start however. when I turned the ignition on the gauge did not move. when I turned on the switch, it did not move.

I originally had a wire from the lag on the resister also to the F term on the VR, but it would spark when I tried to install the + ground battery cable. I quickly learned that was in-correct.

Re: Farmall H Wiring

Sun Mar 20, 2011 8:57 pm

You need a wire from the regulator side of the ammeter or from the L term of the regulator to the light switch and ignition switch.

Re: Farmall H Wiring

Sun Mar 20, 2011 9:03 pm


from the the regulator side of the amp meter? this would be the discharge side?

if I choose the L on reg, where on light switch does it go?


Re: Farmall H Wiring

Sun Mar 20, 2011 9:06 pm

With a voltage regulator the hi-lo charge settings on the light switch are non-funcional. The wire from the ammeter to the fuse holder should be hot all the time. If you are using the fuse holder on the light switch be sure the contact surfaces are clean. They corrode really easily. If the fuse is good you should have power to the light switch. Follow this diagram ignoring the connection to the generator field:


Re: Farmall H Wiring

Sun Mar 20, 2011 9:11 pm


I used that exact diagram, and I still get a spark when trying to install battery ground cable. Fuse is not blown

Re: Farmall H Wiring

Sun Mar 20, 2011 9:48 pm

Go back to the ammeter and remove that wire and see if you still get a spark. If not, the problem is in the light circuit. If you still get a spark the problem is somewhere else. Start disconnecting wires until the sparking stops. The last wire you removed will lead you to your problem.

Re: Farmall H Wiring

Mon Mar 21, 2011 4:19 am

Bigdog, JOhn,

I am down to getting lights to work. When I pull out ignition, the amp gauge discharges as it should. Do the switches go bad? The lights worked before I began :( . I made sure the light wires are on correct terminals and they are. I also made sure the coil resistor was not touching anything or the switch itself. once in a while when I put the + cable on the bat. it sparks, but not all the time. when the light switch is turned on I have no lights nor does the gauge move.

Re: Farmall H Wiring

Mon Mar 21, 2011 6:45 am

Connect the wire from the fuse lug to the L terminal of the regulator. Switches do go bad. Do you have a volt - ohmmeter? That or a test light will help us troubleshoot this.

Re: Farmall H Wiring

Mon Mar 21, 2011 9:46 am

Switches do go bad, but usually you can rock them back and forth and get a connection. What happens more often is the clips that hold the fuse get some corrosion on them and it loses connection. clean the inside of the clip[ good with a fine brass brush, or temporarily use a clip to bypass it. One other thing, do not overlook the ground on the lights. If you have painted them you may not have a good ground, either where they mount or inside the light. If it is the tear drop light there is a little copper strip inside the light that presses against the side of the reflector for the ground.

Re: Farmall H Wiring

Mon Mar 21, 2011 12:46 pm

To all those who helped - THANK YOU! problems seemed to be fixed. fuse holder on the 4-post switch was dirty.
Tractor fired right up and lights worked.

Thanks Again