How to Test a John Deere Voltage Regulator (5-Step Guide)

The voltage regulator controls the electrical current coming from your John Deere lawn tractor’s stator so that its battery will be charged with a smooth current that won’t damage it. Thus, it’s critical to test it regularly to verify that it’s in good functioning order and that, if a problem arises, you can address it quickly to prevent more damage to your vehicle.

In general, you can use a voltmeter to test a John Deere voltage regulator with these steps: 

  • Locate the voltage regulator 
  • Connect the voltmeter’s black lead to the ground 
  • Connect the voltmeter’s red lead to the furthest prong 
  • Transfer the red lead to the middle prong 
  • Transfer the red lead to the closest prong 

In this article, let me discuss how the voltage regulator works and give you more details on the process of testing your John Deere voltage regulator.

5 Steps to Test a John Deere Voltage Regulator

John Deere old tractor

When you test the voltage regulator lawn mower, knowing how to use a voltmeter is required. Now, let’s test the AM102596 John Deere voltage regulator as an example. Here are the steps:  

Step 1: Locate the Voltage Regulator

Park your John Deere on a hard and level surface. Then, set its parking brake and remove the key from the ignition. Raise the hood and look for the voltage regulator on the right side of the engine. You can locate the regulator in the little silver box attached to the engine’s side.

Step 2: Connect the Voltmeter’s Black Lead to the Ground 

Disconnect the voltage regulator’s plug from the bottom. Then, turn on your voltmeter and set it to the Ohms scale. Look for the ground wire under the bolt that secures the voltage regulator to the engine block. Connect the voltmeter’s black lead to the bolt with the ground wire underneath it. Then, you can find three prongs under the regulator.

Step 3: Connect the Voltmeter’s Red Lead to the Furthest Prong 

Connect the voltmeter’s red lead to the prong furthest from the ground. The voltmeter’s reading should be 31.2 M. If that isn’t the result, you should replace the voltage regulator. But continue to the following step if the reading is correct.

Step 4: Transfer the Red Lead to the Middle Prong

mechanic with black gloves testing battery with multimeter at 9.69 reading

Maintain the black lead on the ground while moving the red lead to the middle prong. The voltmeter’s reading should be in the range of 8 to 9 M. If not, the voltage regulator should be replaced. Continue to the following step if the reading is correct.

Step 5: Transfer the Red Lead to the Closest Prong 

Still, keep the black lead on the ground and move the red lead to the prong closest to the ground. Examine the results. The voltmeter’s reading should be between 8 and 9 M. If that’s not the case, the voltage regulator will need to be replaced. But if all of these readings are correct and within the standards, your voltage regulator is in good condition.

Bonus Step: Test Through Its Battery

You can also perform a John Deere voltage regulator test through its battery voltage. Here are the steps:

Step 1: Set Up Your Vehicle 

Make sure you park your vehicle on a flat, hard surface. Turn the ignition key to “off” and set its parking brake.

Step 2: Load the Battery 

Return to the “neutral” position with the foot pedal. Then, raise the tractor’s hood and turn the ignition key one position over to turn on the mower’s headlights without turning the engine over for 15 seconds to put a slight load on the battery.

Step 3: Set and Connect Voltmeter Leads to the Battery 

Turn your voltmeter on. Then, set it to the 50 DC scale. Connect the voltmeter’s positive red lead to the battery’s positive (+) terminal. Then, connect the voltmeter’s negative lead to the battery’s negative (-) terminal.

mechanic with black gloves testing battery with multimeter

Step 4: Check the Voltmeter Reading 

Start your vehicle’s engine and set the throttle to its fastest position. Over five minutes of operation, the battery voltage should remain between a 12.2- and 14.7-volts DC reading.

FAQs

What exactly is John Deere’s voltage regulator (for a lawnmower)?

john deere mower

The voltage regulator of a John Deere lawnmower ensures that the machine’s battery receives a steady, continuous charge. It runs on a 12-volt system to keep its battery charged. To send back to the battery, the stator on top of the engine must generate 14 volts. The 14-volts must first pass via the voltage regulator, which evens out the voltage-current, ensuring that the battery and electrical system are not damaged. (1)

In my example, which is the AM102596, it’s a voltage regulator used on single-cylinder Kohler engines seen on John Deere lawn tractors. The voltage regulator regulates the electrical current flowing from the stator, ensuring that the battery is charged at a steady rate that will not damage it. (2)

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References
(1) electrical system – https://www.britannica.com/technology/electrical-system
(2) lawn – https://extension.umn.edu/lawncare/environmental-benefits-healthy-lawns

About Sam Orlovsky

b1d87d2ee85af3e51479df87928bdc88?s=90&d=mm&r=gI realized early on carpentry was a huge passion for me and I’ve stayed in the industry for over 20 years now. This gives me a unique ability to really be able to tell you what the best tools and recommendations are. I’m not only a carpenter but I also like machinery and anything to do with electrics. One of my career paths starting off was as an apprentice electrician so I also have a lot of experience with electrical products and anything related.