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How Do I Troubleshoot an Onan 300-5374 Generator Board?

There is a temptation to assume that any problems with your Onan 300-5374 generator will be with one of the larger parts -- perhaps a mechanical component. However, any problems you experience are as likely to be with the electrical parts of the machine as the mechanical. Checking its control board will allow you to troubleshoot many of these electrical components and ensure that it keeps delivering power to your Onan generator.

Things You'll Need

Screwdriver
Digital voltmeter
Jump cable

Instructions

- 1
  Use a small screwdriver to remove the panel on the front of your Onan generator. This will give you access to the circuit board, at which point you can perform a couple of simple tests.
- 2
  Use your digital voltmeter and connect the negative lead to ground and the positive lead to the positive battery cable on the starter solenoid. Read the battery voltage -- a fully charged battery in good condition should read 12.6 to 12.8 VDC; if this is not the case then charge your generator's battery.
- 3
  Check the control fuse, a 5A Slo Blo, if the engine will not crank when you try it. Have the fuse replaced if it has blown or is damaged or badly connected. You will be able to find a registered dealer listed in the User̵7;s Manual, or you can contact an electrician who will be able to replace the fuse for you.
- 4
  Check for wiring damage if the engine is cranking but the generator is still not working properly. This damage will be most noticeable if wires are frayed or split or they aren̵7;t connected to anything. An electrician should replace any loose or damaged wiring.
- 5
  Use a jump lead to connect the battery positive pin to the starter solenoid. If the engine cranks then it means the board is defective. In this case, consult a registered dealer or expert on these matters using the methods suggested in Step 3.

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