How to Test G8 Yamaha Regulators

The purpose of a regulator, including G8 Yamaha regulators fitted to their gas powered golf carts, is to control the voltage supplied to the electrical equipment. The alternator that makes electricity to power your electrical equipment produces variable voltage, depending on the speed the rotor is turning. For example, when it's turning slowly it only produces a few volts, but at speed the voltage can increase substantially. If the output isn't regulated, then your electrical equipment gets damaged. You can easily test your Yamaha regulator using a multimeter.

Things You'll Need

  • Multimeter
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Instructions

    • 1

      Remove the cart seats. Open the clips on the side of the seats using your fingers, then lift off the seat. Open the access panel to your battery. Rotate the knurled screws 90 degrees counterclockwise using your fingers, then lift off the cover.

    • 2

      Read the label on the side of the battery to determine its voltage. Your Yamaha regulator is set to restrict the voltage to about 2 volts more than the battery output. So if the label on the battery reads 12 volts, then the regulator limits the voltage to about 14 volts.

    • 3

      Turn on your Yamaha engine and let it run at idle speed. Set the multimeter to measure voltage.

    • 4

      Hold the two plastic prongs from the multimeter in your hands. One is red for positive, the other black for negative; both have metal sensors on the ends.

    • 5

      Place the red sensor on the battery terminal labeled "+" and the black sensor on the battery terminal labeled "-." Read the multimeter display. It reads the same as the label on the battery, if your battery is fully charged; it may be a few volts less if the battery isn't fully charged. This is because the alternator isn't producing high voltage, as the engine is at idle speed -- so the Yamaha regulator doesn't need to cut in and the voltage you're reading is the battery's voltage.

    • 6

      Increase your Yamaha engine speed so it's running at about half its maximum speed. Read the multimeter display again. It now reads about 2 volts more than the label on your battery if your regulator is operating correctly. This is because the alternator is now producing voltage much higher than the voltage from your battery. The Yamaha regulator has cut in to restrict the voltage. If the reading is the same as the first reading, you may have a problem with your alternator. If the reading is more than about 2 to 3 volts higher than the label on the battery, you need to get your regulator checked as soon as possible or your electrical equipment will be damaged.

    • 7

      Remove the sensors from the battery terminals. Reduce the engine speed to run at idle and turn off the engine. Replace the battery cover and turn the knurled screw 90 degrees clockwise using your fingers. Replace the seats and clip them back into place.