How to Test a Tractor Generator

If your tractor's generator isn't working, it can be quite frustrating. Fortunately, troubleshooting this part of the machine is something that can be accomplished by someone with a basic understanding of how the equipment works and the assistance of a simple tool called a voltmeter. Provided you take some safety precautions, testing the generator is very doable for the layperson. From there, you will be able to determine whether you need a new generator, can repair the existing one or if something else entirely is behind your tractor malfunctioning.

Farmer on tractor
credit: mrs/Moment/GettyImages
How to Test a Tractor Generator

Before You Begin

Before you begin working on your tractor, be sure that it is parked on a sturdy, level surface. Use the parking brake if one is available and place the tractor in neutral. Preventing the machine from sinking into the ground or rolling away while you're working on it is important.

In addition, you should be sure that the key is not in the tractor's ignition. Until you are ready to test the generator, it's important that the equipment is not turned on. Remove the key to avoid any potential problems while you are locating the generator.

Testing the Generator

To test the tractor's generator, you will need a voltmeter. This device is used to measure the voltage across a circuit. In this case, that circuit is the generator. You'll need to set the voltmeter to the appropriate voltage, which depends on your tractor. You may find that 50 volts are appropriate.

Place the key back in the ignition of the tractor and turn on the headlights. This will enable some power to flow through the generator so that you can test it.

Next, find the voltmeter's red lead and touch it to the positive terminal. Use the voltmeter's black lead to touch the negative terminal of the generator. This should provide you with a reading of the voltage across the generator.

Then, you may turn the tractor's engine on and let it run for a few minutes. During this time, the voltage should remain fairly consistent.

Troubleshooting a Faulty Generator

If the voltmeter doesn't show a reading while you're using either the lights or the engine on your tractor, the generator's brushes might be excessively worn. Try to apply some pressure to the brushes while the engine is running. This might make the voltmeter reading increase. If that's the case, it's possible that the brushes might be too worn to exert adequate pressure. Replacement of these parts or of the entire tractor generator may be necessary at this point.

Danielle Smyth

Danielle Smyth

Danielle Smyth is a writer and content marketer from upstate New York. She holds a Master of Science in Publishing from Pace University. She owns her own content marketing agency, Wordsmyth Creative Content Marketing (, and she enjoys writing home and DIY articles and blogs for clients in a variety of related industries. She also runs her own lifestyle blog, Sweet Frivolity (