Checking a generator

If it isn't showing voltage in this range your regulator or generator is the problem.
I think you have a generator problem since the engine should run off the generator if you remove
a battery cable. Put the red test lead on the armature post, it may just have an A stamped near the post and ground the negative lead. You can do this with the engine running at a fast idle.
you should read the output voltage of the generator. I have my hour meter hooked to mine
and it only reads voltage when the engine is running. Hope this helps. Hal

Although some will argue with this advice, it is best NOT to be pulling the battery cable off with the tractor running.

Check the battery voltage with the tractor revved up to 3/4 speed or so. If the battery voltage is below the range I've listed, check right at the generator "A" terminal. If the voltage is still low there, TEMPORARILY "full field" the generator by jumpering the "F" terminal on the generator to ground. If this brings the voltage up, suspect the regulator, and check the wiring between the generator and regulator. If "full fielding" the generator does not make it charge above 13.5 volts, you have generator problems.

Engine electrical and ignition systems make a lot of electrical noise, which can screw up cheap digital meters, and cause inaccurate readings. I usually use an analog meter around this equipment, or a quality digital meter.