The power pack on your Johnson outboard boat motor is a central part of the ignition system. The power pack supplies voltage to the ignition system's power coils. A malfunctioning or dead power pack can cause your Johnson outboard to have problems at start up. You can use a multimeter to test the power pack. However, because the power pack has varying voltage levels, a peak voltage adapter will also have to be hooked up to the multimeter.
Items you will need
Multimeter
Peak voltage adapter
Connect the peak voltage adapter by plugging its test leads into the positive and negative jacks on the multimeter.
Plug the multimeter test leads into the voltage adapter.
Turn the multimeter on and switch the power to the "DC" or "Voltage" setting. Also set the voltage range to at least 150 volts.
Locate the wires that run from the power pack to the power coil. These wires are typically colored orange or white. Locate the positive and negative terminals. They will both be marked clearly. Touch the positive and negative test leads to the corresponding wires connected to the power coil. The voltage reading should be at least 150 volts. If not, replace the power pack.